"I am 10 days late on my period and it always comes regularly, i have slight lower back pain and a very mild ache in my lower abdomine. Could I be pregnant?"

If you have been having sex, then yes, you could be pregnant. Periods can be off once in awhile for a variety of reasons, or no obvious reason at all, even if it has never happened before. Obviously there would have to be a first time if it were to happen... :)

Have you tried a pregnancy test? That would be the first step. If it is negative, wait another week and try another if still no period, or wait until next month when your period would normally be due and see what happens.

If it would give you some peace of mind, go to your doctor's and see about having a test done there. The in office urine tests are usually no different from what you could buy yourself however. They may or may not decide to have a blood test done as well.