I only stayed on my cycle for 2 days. My boyfriend and I had sex Saturday and that's when he ejaculated in me. Sunday I woke up to a cycle but it only lasted two days could I be pregnant?

Its been less than 5 days... so its far too soon to know or even test. You will have to wait until your next period is at least two weeks late before you can test.

Yes it is possible, thiis is how it can happen.

Good luck, since it appears you are trying to conceive
You are going to have to just wait, most likely wait till next month and see if you miss that period also..