third tri is hard because the exhaustion kicks in, your uncomfortable AND add in the the ridiculous heat we are having...no wonder you are grumpy (me too!!!)
Try to remember you planned this baby and all this crap we have to go through to get to the end IS worth it!!
I am a lot more irritable this pregnancy as well as people tick me off more when I know I would normally be fine (I have no patience for my toddler right now when I normally have a ton).
Hang in there, the weight will come off and when your baby is here, you'll be happy you did all of this