Negative test. - pregnancy symptoms

I was just wondering if anybody has been experiencing any of these symptoms or could share some advice...

Back in Feb I had taken the depo shot however me and my partner had unprotected sex within the first 5 days of it. 

I've taken several pregnancy tests and they have all come back negative. Over the last three weeks I have had continuous light spotting (light pink) I went to the doctors they prescribed me with some tablets to take to calm the bleeding however there's no difference. My doctor is finally sending me for some blood tests on Friday to see what's happening. It's just I feel all the pregnancy symptoms I feel bloated constantly, my breast feel and look huge and really sore, feeling sick and different points through the day. 

If anybody is experiencing anything similar or has any advice id be much appreciated just want to know what's going on. And if i am pregnant then does the depo affect anything I just want to be in the best health for me and possibly for the baby.

Thanks in advance