Help! Maybe prego?

Okay so my obgy put me on provera to help my periods stay regular and to get pregnant. I start taking them on the 1st of the month and end on the 10th of the month. (We have been TTC for 4 years) when on the provera I normally start my period on the 9th of every month. Well this month no period! My DH and I have been BD a lot because we really want a baby. So it is now December 19th (10 days late) I'm nervous to take a test because I don't like to get my hopes up and then it be negative. And plus when your buying them a lot it really starts to cost a lot of money! So what do you all think?!  I have also been pretty nauseous (usually only at night, just like my first pregnancy that ended in a miscarriage) loss of appetite, and very tired! I have been taking a 2-3 hour nap almost every day and I never take naps!