feeling bad for being irritated ....

Morgan
My SO & i have been together for almost 5 1/2 years & have had a pretty good relationship . He just engaged to me in June actually .. 2 weeks before we found out we were pregnant.!   This is our first baby, im 29 weeks along! When i found out i was pregnant; one of the first things that ran through my mind was .. How i know so many friends of mine .. Who's relationships seemed to fall apart .. While they were expecting .. Or somewhat shortly after having the baby .. Idk. I guess what i'm saying is i'm just scared that could happen to us .. :(
& i feel like the past week i've just been Really irritated with my Significant other .. & i feel bad afterwards .. Ugh, i feel like my horomones are just getting the best of me .. 
Obviously he's seen me pissy & irritated before. I just hope i dont push him too much :( 
Sorry for the long rant .. I just hope i'm not the only one that feels this way ! 😩😥
Any suggestions on how to not be so irritated..? 😳