If you're scared that your mother with be mad about you having sex...... more than likely, you're too young.
I think Blu's point is good, but will also mention that doctor-patient confidentiality rules would prevent a doctor from gratuitously blabbing such a fact to a mother of a teenager.
How old are you? I think that telling your mom that you are not a virgin anymore is important. That way it opens up a whole new world of things she can tell you that are helpful to a sexually active (hopefully) older teen. Blessings - Blu