2yeara trying

It's been 2 years ttc for our second baby. We haven't had any luck. My husband has a daughter from previous relationship and we have one of our own. I went to the dr got an ultrasound blood work etc everything looks good with me. He hasn't got checked and he's the type that hates drs. My 7 year old just said to me this morning." Oh man, I'm never going to have a brother" I just wanted to cry because I want to give him siblings. I just told him. " just pray to go to give you a brother and sister" pray hard, god will listen to you.... I stop and think like one day it will happen but when. My son is 7 and is pretty much an only chil since sister just visits. Sometimes I think, what if we just can't have any more?