Breastfeeding and losing weight

It's trickier the older your baby gets; you'll probably have to experiment. The most important thing is getting good nutrition; after that, you probably don't need more than an extra 200-300 calories a day if your baby's not exclusively breastfeeding. I found that I could pretty much just ignore the whole bf calories around a year, maybe eat an extra apple or something if I felt particularly hungry that day.

If you're looking in MFP, "breastfeeding" is listed as a negative calorie food (weird, I know), or you can just set your goals customized to give yourself some extra calories.

That's awesome you have nursed for 10 months!! I nursed for 13 months and just weaned about two weeks ago. I had the exact same question--I even asked some trainers and they all stated to stay around 1200 calories no matter what blah blah blah. I did a lot of research on nursing, calorie burn, exercising, weight loss etc. and from everything that I read it said not to diet just to eat healthy etc. Well I'm the type that needs to keep track of my calories so at 4 months postpartum I started training and eating around 1400 calories. I lost a good amount of weight....and I can honestly say I wasn't really strict on calorie counting because I also trained for a tough mudder event and sometimes I was just starving so I ate because my body was telling me to. Plus, I didn't want it to affect my milk supply because I was solely nursing and didn't want to introduce solids until 6 months of age. From everything I read, research says you can burn up to 500 calories a day just nursing. However, I did not account for those extra calories in my diary.
What I did find, is that as I introduced finger food (9 months of age) and as nursing sessions naturally decreased, my body regulated itself so efficiently, it was like it wasn't even burning the extra calories at all. I even gained weight because I was being slack with my eating. So in my experience my body regulated nursing. I still stayed around 1400 calories so it didn't affect my milk supply...and was still able to lose weight (especially the weight that was creeping back on). I think the most important thing is to not worry about staying too low-calorie, but finding a happy medium that allows you to lose weight (if that's what you are wanting to do) and not to affect your milk supply.
I hope this helps a little...let me know if you have any other questions!