I think this might be insomnia but I'm not sure ...

This sounds miserable for you and won't help with your studies. And it sounds like insomnia!
Are you taking any meds for your ADD/ADHD? If so, talk to your doctor as they may cause a problem.
Otherwise:
1.get into an evening and bedtime routine - bath, pyjamas, warm drink, a bit of light TV and stick to a regular bedtime. Have a little ritual that relaxes you.
2. Make sure your computer, TV, any exercise stuff etc are all either not in your bedroom or well out of the way and don't use them in the evening. These are all waking activities, not sleeping activities.
3. Make your bedroom a sanctuary for sleep - do it out beautifully (if it isn't already) so that you really want to be there and sleep there.
4. Try a sleep mask and ear plugs to block out any noise that may keep you awake.
5. Keep a journal of your sleep patterns, evening routines, stresses etc.
And if all else fails, talk to your doctor. Sleep is essential for all of us.

I did used to take an ADD medication and when i stopped , nothing changed. I have at 2 year old brother so I don't think that there's much oom for a routine, but I'll try! And the journal sounds like a good idea-I'm going to try that! Thanks!

Starting tomorow night haha

I must give up the idea of a routine, because I share a room with my younger sister and she refuses to cooperate. Any other ideas?