I was on that pill for about 6 months.....the reason I came off it was because my periods were all over the place.
With it not being like a normal pill, (with a 7 day break) theres no actual indication as to when you should expect your period......atleast, not until your body has had time to adjust to a pattern.
In your case, you have only been on it 6 weeks, so I would assume your body is just trying to adjust to all that progesterone.
I too had the implant, which I had removed after 9 months due to bleeding constantly. The implant is progesterone too.
You may find progesterone-only contraceptives mess your cycles up. They certainly have with me.
Whilst achey boobs and back are a sign of early pregnancy, its amazing what the side effects of these little pills can have.
I guess the not knowing is the hardest bit, and waiting around is really tough....but the only way you'll put your mind at ease is to take the test. So good luck for Tuesday!
your late on it.... and i heard its not a very good form of birth control..your goign to need to take a test