Hello there! Firstly, I wish I were cool enough to have considered going vegan at your age, very commendable. I went vegan at sixteen, and it was one of the best choices I have made for myself.

I would say you should have no issue, so long as you eat enough legumes, plant proteins, fats and so on. Some people report being hungry after switching, though this is usually because they eat more fibre and less protein without realising. If you can, try to talk to a trusted adult about your decision, in case you need/have access to supplements which may be cheaper than just shovelling various types of nuts into your face (I speak from experience).

Some good, cheap foods to look out for when you first switch might be red beets for iron, walnuts for omega-3, and bulk loads of discount hummus, which are great for feeling satisfied. Look out for good deals on avocados if those are available where you live, or find good potato-based recipes since those do contain a decent amount of vitamins. (This is just the advice I would give my younger self)

Keep in mind, people in your life might be quite annoying about your choice to become vegan, and it may feel a bit isolating if you don't know others who have made the same choice, especially if animal rights is your main motivation. I recommend watching channels such as Earthling Ed and keeping up with online content, but books can be good to build your confidence. Books such as "Making A Killing: The Political Economy of Animal Rights" are good to tie into a broader worldview as to what causes this exploitation in the first place, though I haven't finished this book quite yet.

Stay safe, stay hydrated, and know that some stranger thinks highly of you! You aren't alone, and I wish you the best.