I personnaly haven't nurse my kids as long as you have - congratz on that. My sister and I both have 2 1/2 year olds... she is still nursing her daughter and we both found out in Nov we were prego. Unfortunatly, she lost the baby at about 5 weeks... but she has also had multiple miscarrages through out her attempts, but does have 5 children. This will be my 5th.
I do how ever have POS... which means it is harder for me to get pregnant. Or atleast that is what I was told in 2001 when I just had one kid (then 6 yrs). Actually I was told "You were lucky you had you child at 17, I don't think you will ever be able to have children without assistance & even then chances are not good. Your eggs don't develope properly & because of that don't ever expect another child." It took from 2000 (when I stopped getting the shot) to around July of 2003 to get pregnant, when I had a girl in Mar 2004. Then I had a boy in Jun 2005 & 2007 and now I'm expecting in July.
Please don't get down about it or stress... I know we all have plans, but sometimes it's not ment to happen when we think it should for whatever reason. But if anything... I've learn what's ment to happen, will happen when it's suppose to. 9 yrs and 3 kids ago I was told never to expect to have anymore kids (not by one but two doctors) - and look at me now... I'm expecting another one.
Keep doing what is best for you and your baby, when and if the 3rd child is ment to be it will happen. Good luck!