young ram doesn't seem to be growing

I am new to sheep and I currently have 2 mixed hair sheep. A female that is somewhere around 2 yrs old and has never been bred and a young ram that it starting to look grown. His 'man parts' have become very pronounced and his horns are about 2" from the scalp. He got to this point a few weeks back and has seemed to grow since. He is still much smaller than my ewe. I am wondering if this is normal or if there is an issue here. They are on a rotational graze system and he is always eating so I don't think that's the problem. Any advise is welcome

I recall last summer when my Blackbellies were a few months old, they seemed to quit growing in the heat of the summer.  It was fall, or maybe even winter, when they seemed to get noticeably bigger, and the ram started to show some interest in mating.  He won't be fertile till it cools off anyway.  I would just wait and see....

Wow thanks. This really helps. I am use to hogs and chickens. With them if they aren't growing there is an issue. It has been very hot. I am in south Louisiana so I am sure you are right