Starting eve with an irregular cycle should I be worried?

So I started eve to better keep track of my period after my phone calendar glitched and I lost track of my cycle. I started keeping better track of it to plan when my boyfriend would visit. But after having sex I had a very heavy period for me. We're long distance so my sexual activity has long gaps. A friend said changes in periods can occur based on sexual activity.

I guess my question is, until eve can get more information should I be worried about being a few days late? I did have a full fledged period after sex (unprotected).