First of all, you should change your profile name to Beautiful Angel 😍😍 - it may not seem like things are going your way now, but just hang on and you will get there! What you have been through is quite traumatic, and most people will have no idea what you're dealing with and how you feel.
When I first got my ostomy, I couldn't even look at it without feeling sick to my stomach. The home care nurse changed my appliance for me at the beginning and eventually encouraged me to do a little bit of the change myself, and I gradually did more until I was doing it all on my own. It was frightening to me (and I'm a nurse!). All I can say is take one step/day at a time, and before you know it, you will be able to change your ostomy with your eyes closed!
As far as your body image - it will take time to accept your new body. Allow yourself to feel sad at times, but don't dwell on those feelings too long. You are much more than your ostomy! This is a good time to start practicing gratitude - think of three things each morning that you are grateful for. It can really help turn your attitude around to a more positive one.
This is a wonderful site for support. We have many amazing friends on here who care and understand. They can be a great source of information and support. You are young, so I would suggest finding some other people your age with the same condition (this site is a good start) to talk with. It helps to feel as if you're not alone - which you're not - we are all here for you!
Hang in there and please reach out with any questions or just to vent! There are so many of us that want to help!
Earth Angel 😇