I was dating a guy (#1) who things weren't working out with anymore. The last time I had sex with guy #1 was March 14th. I got my period on the 22nd of March which lasted until the 25th of March. I started dating guy #2 and we started having sex almost everyday from the 25th of March. Right as I got off my period. I went to the doctor and had an ultrasound on May 10th and the tech told me I was measuring 8 weeks 0 days. Would it be guy #2's baby? I've always had semi-regular cycle periods.