To stay warm, it all starts with a good base layer that wicks moisture away from the skin. Good socks make a big difference, you want layers that hold the warmth and get rid of the moisture. Get rid of the cotton long johns and get some of the modern stuff like Cold Gear or Cabela's camo skinz or Xscent base layers....there are a bunch of great base layers out there. Most of the silk weights will keep you cool when its warm also.
As far as draw weight, if you found out that you can't pull back your bow while hunting, I would think maybe you haven't been practicing enough. You can't stop practicing just because season started. I shoot every day before I hunt, even if it's only 3 shots. When you haven't shot for 3 or more days, that first draw is hard. By the 5th shot, it's a little easier. As you get older, arthritis sets in, it takes a few more shots to loosen up. lol With weather changes may come little bow noises. Before leaving the truck to hunt, I always draw my bow back and hold a draw for a few minutes. Gets the blood flowing, check to make sure nothing is squeaking, get the kinks out and find my anchor point. If you are cold in the stand, it's a great time to do a few minutes of practice. Draw your bow, turn different angles for different shots, while holding your draw till you're good and warm.
I did the same thing my first year. Stopped practicing and just hunted. I shot 5 deer in my 1st 2 months, then winter season, after about 3 weeks of no shooting, a Big buck steps into range and I can't draw. It took me 3 times to get to full draw, I almost didn't get a shot and had to take a 35 yard shot instead of a 15 yarder.
A good friend of mine had the same problem but he got a bow flex. Problem is his wife now has the bow flex body, his is still in the closet. lmao If he don't start using it soon, he'll be shooting a girls bow soon too.lol I think 35 lbs is the limit.