Yes, it is like going through puberty. There's lots of things that go on that are strange and hard to navigate. They can mess with ones mind. I've had acne, body hair in places I don't want, appetite issues, temperament changes, sexuality shifts (both mental interests and physical sensations), confusions over losses and gains, and so on.
When I first started down the path to top surgery I was very excited then as the day approached I became terrified - not sure if it would be a mistake, if I talked about it with T would she pull her letter, will my wife still be ok with me, will others notice... At the time, T worked for the hospital and clinic where I was having the surgery. She was able to stop in after surgery and visit with me. I think that was a blessing.
Trigger warning - sexual content
At those higher levels, I've also found myself being more self-sadistic/masochistic when I hit that hormone range. The part of me that identifies with my aggressor comes out and I start demanding more from myself and punishing myself more severely when I do not meet some idealized version of "perfection".
Since you've talked about weight being a concern of yours, I want to say that with testosterone, I have struggled more with hunger. My body has also shifted to holding more weight/fat around my waist rather than in my hips so when I am up in weight it is more visually noticeable to me. I've always been easy at gaining muscle so I'm not sure the testosterone has had an impact there. I have worked harder at developing my body since starting down this journey and I've loved some of my chest/shoulder/back development. I don't think I'll ever have a "triangle" shape because of my weight/body pre-journey. Something to be mindful of when starting.
Oh - and if you have a family line that genetically leans towards baldness or thinning hair; taking testosterone will likely trigger hair loss for you. Yep, it has great potential to start growing out of places like arms, chest, back, butt... and fall out from your head. Look around your family line to figure that out. As a genetic female, you'll need to look on both sides of the family. On your dad's side, look at your grandmother and your father. On your mom's side, look at your grandmother, grandfather, uncles, brothers, your grandmother's father - to get a clue as to how your body might change hair wise (and to some degree fat distribution as well).
Some things are reversible but others are not. Hair changes are a mixed bag on if they are reversible or not, most are not. Voice changes are not reversible once they hit a certain point of change. Fat distribution is reversible as is the ability to become pregnant and carry a child if that is desired (given no hysterectomy). Also, if no hysterectomy, you are still at risk for all those cancers - meaning you'll still be encouraged to have pap smears.
Sorry this is super long. I don't know where you live, if you live in a large enough city, there should be local support groups. I highly recommend finding one (if you have not already done so). It's a great place to feel supported and to ask questions of all kinds. When you do have your surgeries, you will need help getting around afterwards. If you don't have a support circle, a support group might have something in set up to help out or you might find a buddy that could help out.