I've been on T for almost 2 years. My weight has stayed the same, but I look slimmer. Most of the weight has come from muscles growing. Especially if you've been working out, you will probably notice in due time that your muscles get larger even if you do not lift weights. So, yes weight gain can happen but not always necessarily in fat. On the otherhand, fat redistributes on T. Some parts might seem slimmer before such as your hips and backside. For me, it went to my gut and a bit around my neck. And it IS true (if you haven't had top surgery), that you can/might lose size on your manbooblets. I am pre-top and can confirm this as I've had to move down a size in binding.
Yes, appetite does indeed increase. The only thing to be mindful of if you are aiming to stay fit is healthy foods. Listen to your body. I've noticed along my journey that my preferences have changed and wants more protein and iron rich foods. It's probably because of the muscles growing. Everything eventually breaks down into glucose for mind/body functionality. Straight up sugar tends to go straight to fat stores. Lean protein is probably recommended as your body changes. In moderation as well, as too much turns into fat stores.
You'll be fine.
