First, congrats on a new therapist. And they sound like they could be a good one, so that's great.

To the rest of your topic, periods suck. I usually will get temperamental/depressive as well as horrible "aching" up there about three weeks beforehand. It's like waiting for a dreaded day that never seems to come.

I tried some birth control a while ago, but the hormones it it made the "aching" a million times worse. Oddly enough, the mental side was somewhat calmer? There might be a low hormone birth control that could help if you aren't planning on going on T at this point, but I'm personally avoiding it like the plague until I can get more solid research on side effects. Good luck either way.
As for hair, when I was in middle school and had my first "real haircut", I just had my hair cut a few inches from waist length (I would have went shorter, but long story). Anyways, I saved a piece of it. It didn't really feel like a part of me died, but more like I was moving on from that part of me, a part that I "outgrew" in a way. I was happy with those few inches cut off though, and just kept going shorter over the years until I eventually had the hair I have now (short/shaggy). I haven't felt that way since that first haircut though, I'm just happy with short hair now. My hair is somewhat thick, and my hair person recommended a unisex hair manipulator for me as I wanted it too look "puffier?". I wouldn't know how to make your hair appear thicker though. Depending on how short, blow drying upside down can add volume sometimes. I say Google can be pretty interesting at times, hope something works.