Hi. So my boyfriend and I kind of played around 2 weeks ago because it was the start of our summer break (college). He had a condom on and stuck it in to pretty much just past the head of his penis... He didn't ejaculate, and it was only for like 20 seconds. It was 2 weeks after the start of my last period, but my periods are irregular (sometimes they don't come until like a month and half after my last one)... could I be pregnant?

If he used a condom the entire time (no penetration without it), it would be unlikely that you would be pregnant, but not impossible. See what happens when you might normally expect a period. If nothing after a couple of more weeks, you could always try a pregnancy test.

Save yourself some panic and either refrain from sexual activity (avoid getting into a situation where things could go further then you plan), or be sure that both of you are using reliable birth control to lessen the chances of an unplanned pregnancy.