I have to say that what you pump and what your daughter is actually getting..... are two different things. My dd is 15 mos and she nurses 3 - 5 times a day. I could not pump a thing to save my life if I tried (seriously).... nothing comes out. But I know my daughter is getting what she needs b/c I can see her swallow, etc.
At 10 months - could your daughter be teething? I know my daughter has always gotten extremley frustrated with nursing when she is teething (we are actually dealing with it now -molars are coming in). But if I give her a bottle she is happy to take it b/c she can chew on the nipple - where as mine - she cant!
I agree with the other lady too, pumping at night wont give you a good idea either.... pump in the morning if anything. Drink more water, pump in between feedings, nurse more frequently, etc - these will all help you build up your supply.
And btw, dont get frustrated... you have enough supply - you've been doing it for 10 mos - GREAT JOB!
Also - check out www.kellymom.com - it has a lot of information about nutrition that nursing toddlers need, appropriate weight gain and what to do to build up your supply (natural herbs), etc.