Frustratingly slow weight loss, why?

You have possibly overestimated your TDEE. Remember that these calculators just give you a good estimate to start with...nobody has exactly XXXX calories as their TDEE...you have to make adjustments as per real world results. If your TDEE - 20% is 1,600 calories then that would suggest that your TDEE is 2,000 calories per day...which seems about right as per statistical averages, but perhaps you fall outside of those averages. As per your real world results, you should see a loss close to around 1 lb per week if those numbers were accurate. As it is, it would seem you are losing closer to 1/2 Lb per week which would suggest that your real world calorie deficit is only 250 calories which would put your TDEE at around 1,850.

It is further possible that you have relatively accurately determined your TDEE but you are underestimating your intake...this is pretty easy to do and even professional nutritionists and dietitians have issues accurately estimating intake.

Either way, your real world results suggest that your calorie deficit is only around 250 calories...so if you're fine with your current rate of loss then leave it be...if you want to lose a little faster then find something in your day to day to cut out around 250 calories more per day....should be as simple as cutting out a snack somewhere during the day or spending a bit more time exercising.

Your diary only seems to list food you've eaten, do you have any drinks with sugar, milk, alcohol, protein, fat in that should be going towards your calorie totals? They can make up a large proportion of daily intake.

Thats fine for black tea with no sugar of course. My tea, 1 tsp suagr and 40ml of skimmed milk is 30 cal per cup, so over the coarse of a day they can mount into a significate amount. Also fruit juice or protein shakes can add quite a few calories.

This link, whilst quite harsh, is true.

http://www.acaloriecounter.com/blog/why-am-i-not-losing-weight/

Just a few diary comments.

1 - I see a lot of entries with the serving size in grams. This is good, provided you are using a food scale to measure those grams. Just as a sanity check wanted to confirm when I see something like:
Albert Heijn - Noten-Rozijnen Mix, 20 grams
that you actually are measuring and eating 20 grams. I ask because something like this is easy to just grab a handful and log 1 serving size. The caloric density of these nut mixes is pretty high so it could cause some error.

2 - Homemade items, like this one - Homemade - Geroosterd Brood Bruin, 1 snee - can be hit or miss. Depending upon who created it, it may or may not be the same as your recipie. Hopefully you made this entry yourself to ensure it is accurate.

In general everything seems pretty good. Your entries look like they are generally correct so I would have to guess that serving sizes are a little off. Probably be more diligent in using your food scale and when you have to estimate, try to be conservative.

Anyway, just some ideas. Here is a good read on this type of stuff if you want some more ideas: http://www.myfitnesspal.com/topics/show/1234699-logging-accurately-step-by-step-guide

I took a look at your diary for April and May and kind of took some notes. There were several dates in April where it seemed like your diary was incomplete/missing some meals because your calories for the day were sub 1000 (April 4, 11, 16, 17, 18, 19). In May there were several days with a lot of quick add calories or seemed incomplete for the day (May 4, 11, 12 [quick added 1300 calories], 15 [only logged doritos and one beer], and 24).

Even though you hit your target/are below your target mooost of the time, not accounting for some of those days could make your deficit smaller than you aim for and slow down your weight loss.

This isn't a criticism--my diary often looks similar because sometimes I can be bothered to figure out how many calories I ate at a restaurant, didn't feel like accounting for a day I overate, etc. But I also accept that I won't be losing weight super fast (and I'm ok with that because I get to eat a lot of delicious food and don't feel overly restricted).

Try doing the 5.2 lifestyle Im have been doing this for 8 weeks and have lost 8.5 lb basically eat your TDEE 5 days and the other 2 eat only 500 calories it works and does not feel remotely like a diet!

Hey there! I was looking through your diary and the only thing I can come up with is to maybe for the next few weeks, just buckle down and cut out the chips, sweets, wine (which it doesn't look like you consume on too regular of a basis), and see if you start seeing some results. I'm suggesting this only because I've been experiencing a lull in my weight loss too and I realized as I was looking through your diary that TOTALLY guilty of it too. My weight loss slowed down in the last month or so, which is why I read your post in the first place, so for the next 2-3 week, I'm going to cut out my "treats" even through they fall within in my allotted calorie intake, I'm going to cut them out and replace them with more fruit, veggies and lean protein. Beer and chips are my nemesis, but when I started my weight loss journey I cut out beer all together and I really saw results. Maybe one or two of your "treats" (even though it's within your allotted calories for the day) is holding you back just enough to prevent you from seeing the results you want. I don't know....just a thought. CONGRATS on your significant weight loss so far!!!!! :-)

Another thing you could try is just bouncing your calories around a little. There's not a lot of science around it that I can reference with peer reviewed studies and such , but it works sometimes. I know you said that IF doesn't appeal to you, and that's fine, but what about taking your flat 1600 (or 1500 or whatever if you decide to lower it), translating that to 11,200 calories per week, and dividing those up a little differently? Like maybe 1,200 on rest days and then 1,700-1,800 on workout days? Or try eating at maintenance for a week or so and then get back to your cut. Sometimes your body just gets used to the 1,600 every.single.day, and a little change gets things moving again. Can't hurt, at least.