Ttc my sex life...tmi

Ttc....my sex life... tmi!

My hubby and i have been married 2 years...and have been ttc for pretty much that entire time we never got pregnant but weren't seriously trying. Now we are taking it more seriously since a happy accident doesn't appear to be in our future. What i am worried about though is my husband....lately hes been going limp anytime he pulls out to switch positions and he cant seem to finish in missionary so we always switch to doggy. We thought he was maybe distracted the first couple of times, but this time there was no reason he should have gone limp. It makes things frustrating for us because i dont really know how to process the situation. Idk if he needs to see a doctor about it or if its probably nothing amd we just need to deal with it. Sorry for the tmi