I've had 3 negative hpt and a negative beta test done at 13 weeks which was also negative it read my hcg level was less than 0.1. what are my chances because i have missed my period again this month?

Chances of what?: It's a bit unclear as to timing. When was that 13wk testing relative to now? If you've missed your period again, it's worth taking pregnancy test if you've engaged in unprotected sex. Unsolicited advice: if you want to continue engaging in sex, take some form of contraception. Side benefit of hormonal birth control is regulation of your menses so no more wondering.

This means: you were NOT pregnant at the time of the last test. However, if you have been sexually active since that time you could have become pregnant.

Not pregnant: With 3 negative home tests and a negative Beta HCG, you are not pregnant. Many things can cause you to miss your period and it is now time for your doctor to start looking into what is going on with a full history, exam, and appropriate testing. Hope this helps.