I am suffering a lot from sex-related OCD thoughts. I had been intimate with my boyfriend and since then my head is calling me bad, sl*t-shaming names and it doesn't stop. Also I keep being paranoid about being pregnant, though I'm on birth control and we always use external protection. The googling doesn't help; every woman says they got pregnant despite using 9 types of birth control and every ache, nausea and twitch seems like a pregnancy symptom.
It is making me exhausted and has additionally thrown me into a deep pit of depression again.

I feel like I am filthy and disgusting. It just won't go out my head. I have sweat outbreaks while these thoughts are invading my head. Even am convinced I had a 'conception dream' type of dream.
The thoughts just won't stop and my number OCD is coming back again (touching things several times, scratching my skin to blood)
I can't focus on things like cleaning, cooking, reading. All is revolving around how filthy I am. I don't know how to cope.

Please help