I started my period on March 10th and finished on the 16th, my menstual cycle only last 20 days in between periods. I had intercourse on the 18th two days after my period is there a high chance I can come out pregnant? Also when do I ovulate?

Ovulation isn't an exact science. There's really no way to tell you when you ovulate. It depends on the woman, and for some women it can change cycle to cycle.

There's not an extremely high chance that you ovulated 2 days after your period, but there is a chance. There are women (many women) that have gotten pregnant while they were on their period.

The fact is, any time you have sex, pregnancy is possible. Even with birth control, pregnancy is possible.

So you'll have to wait and see. If you miss your next period then try a pregnancy test. If you're not trying to conceive then at least use some form of birth control. That will lower, not eliminate, the chances of pregnancy.

Good luck.