You'll be doing worse than using MFP as intended which you were doing.

Only thing there is, keeping the deficit reasonable by selecting better weight loss goal amount.

They usually end up the same if the deficit is close to the same, and you average out the whole week.

But no, doesn't sound like you did the TDEE estimates, merely getting rough ball-park estimate.
If you want rough ball-park results, that may be fine for you.

Otherwise, perhaps the spreadsheet on my profile page can help, stick on Simple Setup and Progress tabs only, and be honest.

Ok, so if I have done your spreedsheet correctly, my BMR is 1505, TDEE is 2224, TDEG is 1813. This is without exercise. So to be sure, I should be eating 1813 per day. This is scary lol.

So you don't exercise? Then 1813 is correct.

But you went to the gym - so you didn't fill in the Activity Calculator right. Then 1813 is NOT correct.

Or you meant something else by your phrase "This is without exercise."

And you did include exercise in the Activity Calc and that is in the TDEE therefore, so 1813 is correct.

And agree with above increasing slowly. But don't start from 1200, start from what you truly ate on average, not net, but gross.
You may have been eating closer to 1400-1500 eating back exercise calories, so it's not much of an increase, but don't start below where you really were.

Yeah what I meant was that when I had a 1200 base I added my exercise calories (which were about 200 - 350 cals all together everyday (Running 8.5-10km/h up and down 15-20 mins with HRM 150/ Bike 95-100 RPM from level 8 to 10 up and downs 120 plus weights 30 mins mid to heavy doing 6-8 different exercises 4 sets 6-12 reps added 50 cals because I have been told that weights dont burn anything. I also walk to work about 0.8-1km there and back, 15-20 up hill there (3-4km/h?, 15 back because its downhill, but I never added that in.) So yeah, I was eating about 1400-1500 anyways.

I think the problems started happening when I had a day of no gym, then I dropped my cals to 1200. So according to the work sheet I should eat 1800 cals (not adding exercise cals), but on days I am not at the gym, I drop those cals to 1500 about?

BTW< I filled out the Activity area of the sheet!

You'll notice that every TDEE table, or that TDEE calculator, is asking about your weekly activity.

To get back to a daily level you of course are averaging that back out.

So the fact that some days are rest some are workouts is already taken into account there - you eat the same amount daily.
And correct, with exercise already included, you don't eat that back separately either.

Hence Total DAILY Eating Goal - TDEG.

Don't try to make more out of it, you are confusing yourself.
Read all the things under Your Results, it emphasis that fact. And what you do if you miss a PLANNED workout, and what to do if you do an extra workout.

And whoever said weights doesn't burn anything doesn't know what they are talking about. Doesn't burn as much as cardio done for same amount of time, but obviously there is energy spent lifting something free from the grasp of gravity, including your own weight on standing exercise. If it was the case you didn't burn anything, than moving your mass around daily wouldn't burn anything.

And I hope you added the walking to work in the Activity Calculator. It's total activity, not what you think counts. Sorry I don't have room for the speeds in km/hr, you'll have to translate yourself and see what level it falls in to. Be honest.

And so you would start eating at 1500, and work your way up to TDEE by eating 100 more daily, a week at a time. Spend some time there at TDEE before you bring the deficit back.