We are trying to have a baby, I have some symptoms, I don't know are they menstrual or pregnancy?

Okay so me and my fiancée have been trying to conceive, we began at the end of last month. We have sex about 4 times a week, and he ejaculates in me every time. Well, Lately my boobs have been very tender, a slight change in color of the nipples (I can't really tell), bloated, cramps, pain in my lower back and last week I was naseous every morning. But last night I had very light bleeding.. I thought it was implantation bleeding, but this morning It was darker.. So now I think it's all just menstraul symptoms instead of pregnancy symptoms. I usually don't start my period until the beginning of the month. So I guess my question is can I still be pregnant? Or is this just menstraul bleeding.