I have been on the pill since march 18th and I took it the sunday start. I had unprotected sex on sunday march 25th. Am I protected?

Pill type? For combo estrogen/progesterone: if you start your pills on the first day of your period, then you are protected. If you start your pills at another time in your cycle, you are protected after 7 days. For progesterone-only pills: you can start any time in your cycle. You are protected after 2 days.
Probably, but not... If you started the pill on you first day of menstrual flow, which average about 5-6 days?, you are really only about 1-2 days of the begining of your cycle, so not likely ovulating. So this protection is more likely from timing and not the pill itself. But not 100%! it is recommended adding barrier method /condom during first month or 2...Any concern, consult your doc... Good luck..