If the sex was unprotected even without ejaculation, then there's a risk of pregnancy. Wait till your a week late, you could take a hpt then. If your period still doesn't show up in a few weeks time, i recommend a blood pregnancy test. but then again, it can also be stress that led to delayed ovulation or no ovulation at all. hope this helps.
The eating patterns and stress could also be a reason behind your missed period, but as the above poster mentioned, you could still be pregnant if you had unprotected sex regardless of whether or not the guy ejaculated. Pre-ejaculate can contain small traces of sperm, and all it takes is one!