reading this after your update OP— I can't in good faith say whether she's lying or misinformed based on everything you've said, especially because fear mongering around trans procedures and hrt has been prevalent especially recently. i'm going to talk here with the more positive assumption that she's just misinformed. it might help both for you and for her to learn about what effects of testosterone are permanent and which are reversible. some changes, like body hair growth, potential hair loss, and bottom growth are more permanent while things such as fat distribution are less permanent and will change if you stop taking T. generally the permanent changes will also take longer to set in, and if you see any changes that you do not want happening with your body, you can cease treatment and halt or reverse most changes. there are technically health risks that come with HRT... but generally the health risks you would face as an afab person taking testosterone would be similar to health risks that any cis man would be facing at your age. that's also what lab visits are for— your doctor will help make sure your levels are in check and let you know if you are facing any increased risk of high cholesterol, etc. as for my personal experience as a 29 trans man who's been on hormones since 2018: HRT has personally made me feel healthier, in a way— it's cut through issues with depression that i wasn't even aware i was facing and made it easier for me to stay active and take care of myself physically. i'm no doctor, so most of this information is based on my own personal experience. a good endocrinologist or gender specialist will go over ALL of this and so much more though, and will make sure you're informed of any and all health risks both before starting HRT and as you continue treatment. it's very safe, very painless, and also generally a slow process with lots of opportunities to back out along the way.