See your school counsellor. They will provide you with some help. They can certainly talk to mom on your behalf.

I believe in Ontario you are old enouh to make your own healh decisions. Here you need a referral from a family doctor to see a therapist or psychiatrist. Seeing your family GP anyway is your best start and you don't need mom's approval for that.

So, counsellor and doctor you should see.

Start that journal mentioned above. Document your feelings, the changes as well as the spikes and document what triggered the feelings too.