The first day of my last period was on the 3rd of Nov and it is now 15th of Dec. I am sometimes late, but never 15 days late. Should I worry about being pregnant are not?

Take a preganancy test. No one here can tell you if you're pregnant or not... Just take the test and find out.

If you had sex then yes, it's possible.

The next step is finding out, which you won't do here. We don't know any more then you do.

Get an hpt, use first morning urine.

Good luck.