Hey man! I'm going to keep this short because I want to say so much since I relate so much to you but I don't really know how to say it. Anyways let's get onto this "short" message.
Im 15 and i'm self diagnosed with OCD. Just if you did feel alone about you being self diagnosed don't be cos there are tons of people self diagnosed with OCD or other mental health issues. But I do intend to see a psychiatrist when i'm older but not atm because I don't want it to get in the way of my exams and everything. I ain't no pro on OCD or anything but I can answer your questions some what reasonably.
I wouldn't say ignore your compulsion completely because the anxiety you get from doing that is pretty bad and it can really debilitate you but that's just my opinion. I would say instead of completely ignoring it try to minimize it. So for example you have to walk into your room 10/20 times try and limit that to a lower number. It will still be tough and you may feel anxious because you aren't sticking to a number you feel safe with but after a while you get used to it.
I do live in the UK so i'm not too sure what is different in terms of places you can get help. Since I haven't gotten proper help atm I don't know too much. But I would say just look up places in your area which deal with mental health. But obviously you can go to a hospital but if you don't feel ready for that there are plently of websites where you can talk to people about your OCD. I know of some but they are UK websites so I don't know if they are any help to you.
The way I got help to see my school nurse (which wasn't much help but that's besides the point) is I went to the school counselor and told them everything about it and they recommended me to the nurse. My parents did have to give agreement which was a bit dodgey since they struggle a bit with understanding mental health. But if you have some sort of counselor at your school then definitely go to them.
Could you expand on your intrusive thoughts about religion? But that is only if you feel comfortable with it cos I know how weird and awful thoughts can be when you have OCD.
Message me if you have any more questions or if you just want to talk about OCD with me cos I have been looking for someone to talk to about OCD for a while now. Anyways hope this helped a bit and sorry for living in the UK since that makes giving help a little bit harder xD