I had unprotected sex 11 days before my period i feel tired and weird is there possibilities i can be pregnant?

Short answer...: Yes, you certainly can. Although any time you have unprotected intercourse you can become pregnant, the most fertile time (when you ovulate) is usually halfway through your cycle. So, on a 28 day cycle, thus usually occurs somewhere around day 14. A common range is 11 to 21 days. Good luck!

Yes: Any act of unprotected sex could result in a pregnancy. I typically tell my patients there are no 'safe' days if you're not ready to be pregnant or a parent. Always use 1, if not 2, methods of birth control. If you are super organized and are tracking your basal body temp each morning when you wake, you can do 'natural family planning' but this is going to result in pregnancy 8% of the time.