Any suggestions on how to quit cutting myself?!

looking at porn and masturbation are both normal and even healthy for people your age. Your sex hormones are increasing as so is your sex drive. Your guilt and shame over watching porn and ( I assume) about masturbation is not good. Masturbation reduces depression and blood pressure and is also thought to prevent prostate cancer and heart disease. Many men and adolescents masturbate once or twice a day, and even up to four times a day! If you are watching porn and masturbating then most likely you are having surges of hormones that are making you feel like doing that.

There is no need to cut. I used to cut a lot and it's really addictive and dangerous, especially if you are cutting deep and are doing it to punish yourself. If it bled a lot or reached the deeper layers of skin you may need to go have stitches, and you need to be careful of infections.

If you are feeling this bad, and you are probably depressed, you can go to someone other than your parents for help. Try a school counsellor or your doctor. It sounds like your parents are very unsupportive, or that they at the very least don't communicate well with you. But I'm sure they love you, and don't want you to hurt yourself.

experience with self-harm

I understand what your going though i was.... i am a cutter.. but i only cut when i have nothing else to make me feel better ( 1-6 times a month MAX) But anyways i suggest replacing cutting with something else a hobby,Drawing,reading, ANYTHING! Just try it :)
And you shouldn't feel bad about looking at porn its normal at your age believe me :) your not the only one and no matter what your mother will love you!
Best of luck!
xx