About 3 weeks ago my boyfriend and I were messing around and wanted to have sex but he wasn't fully erect. He did however enter me and proceed to have sex. We did not use a condom. Three days later I had sex with him and used a condom. I've been stressed out since the incident and my period has not arrived. It usually comes every 2 weeks and 5 days and today is the sixth day. Could I be pregnant or is my cycle going to be off because of the stress?
Speaking as a man, and an older man at that, I just want to make it really, really clear that even when we're not fully erect men are perfectly able to produce sperm either in pre-ejaculate ("pre-cum") before we have an orgasm or in semen when we ejaculate. And yes, we're also perfectly able to ejaculate without a full erection.
Check out the last couple of questions in the Scarleteen Pregnancy Risk Assessment for Vaginal Intercourse if you're not sure, but
If you DID have unprotected penis-in-vagina intercourse but the man DID NOT ejaculate, then you have a LOW TO MODERATE risk of pregnancy. If it has been less than 120 hours since your risk, you may obtain emergency contraception. If it has been greater than 10 days since your risk, see your health care provider as soon as possible for a pregnancy test and an STI screening.
If NOT, keep reading.
Did you have unprotected penis-in-vagina intercourse (no condom, no other birth control of any kind), including ejaculation into or onto the vagina or vaginal area?
If you had unprotected vaginal intercourse including ejaculation into the vaginal or on the vaginal area, then you have a HIGH to VERY HIGH risk of pregnancy. If it has been greater than 10 days since your risk, see your health care provider as soon as possible for a pregnancy test and an STI screening.
Since you mention having had sex again "three days later" and that your period "still has not arrived" you might be cutting it close, but emergency contraceptives like Plan B can still work up to five days after intercourse. If you're still inside that window then you should try it if you possibly can. Otherwise I'm afraid all you may be able to do is go for that pregnancy test to see if it's pregnancy or stress.