I had protected sex yesterday on my period. im still on my period today, my period is suppose to end on monday, if i continue to have my period tomorrow does that mean that im not pregnant?

Please be aware that anytime you have unprotected or protected sex you can be pregnant recommend checking a pregnancy test every three days till it's been a week after normal. Also use contraception safe sex

No. Having sex during your period is not necessarily a safe time and the duration and quality of your current period is not predictive in any way. You will have to wait for your next period to know for sure you have not conceived. With a normal 28 day cycle you should be relatively early and at low risk, and use of protection obviously further reduces your risk.