I know I posted this in the pregnancy forum, but i'm in desperate need of help...

I had a tumor in my thyroid and had to have it removed, so now I take a synthetic thyroid pill called levothroid.

I know it was extremely stupid of me, but I fooled around with my boyfriend 2 days after my period was finished. We lay naked in bed, simply kissing, and by the time I knew it, he was rubbing his penis against my vagina. He pushed slightly against my hole, and felt he was about to cum. So he pulled out and came, but he came nowhere near my vagina.

Although he did not ejaculate inside of me, i'm scared that some precum might have slipped into me somehow.. I've read that precum can sometimes carry sperm..

I was hoping to take a plan b emergency contraceptive pill, but i'm afraid it will interfere with my levothroid.

I don't know what to do.. I'm only 17 and i'm the type of girl that never does these types of things.. I got so lost in the heat of the moment.. I don't want to get pregnant.. I'm so stupid..

What should I do? Should I take the plan b pill without telling my doctor? I'm afraid it might mess with my hormone levels.. Should I call my doctor? I don't know what i'd say...
Should I wait a month to see if I miss my period?
Should I wait a few days before my actual period and take a "first response" stick and check my urine for pregnancy hormones?
And then have an manual vaccum aspiration (mva) done?

I'm sorry if I sound whiny and irritating with all my worrying and questions, but i'm so lost right now.. I don't want my parents to know.. They'd kill me.. They trusted me.. But I don't know what to do.. I need help.. I'm so scared..

-possiblypregnant