I'm pretty close to one of my teachers, she was there for me through difficult times such as coming out because she'd been there and done that so we naturally bonded over it. We were the same, we got on well and talked often about how I felt (because I'm not the most stable of people) and she always made sure she was helping me.
I never saw it as creepy because she's such a lovely woman who I relate to so well, but I tried backing off from her at one point for the exact same reason as you. I wouldn't say I was 'obsessed' but I relied on her a lot and it felt she meant too much to me. However, backing off was one of the worst choices I made. I blocked her out completely after having a bit of a break down on her the previous week. I wanted to deal with my own problems but it only made things worse to be alone. Sure, I had friends, but they didn't understand the same as she did, because I'm oddly mature for my age.
I got worse and worse for weeks and then I realized it was stupid to block someone out if talking to them makes you feel better and happy. So I guess the moral of this little anecdote is that if he makes you feel more confident and cared about, don't push him away, but if you find it a bit creepy then feel free to tell him. He's a teacher, he will understand if you want some space and will be obliged to do so. If you need to talk to him, he will be there until you leave. So by all means, tell him you need some space, just don't block him out 100% if he helps you emotionally.
Hope this helped!