Have been trying to concive

Hi, I have been very confused. I am 23 years old and my husband and i have been trying to concive for over a year now. I had a misscarrage back in December of 08. Ever sence then i have not been able to get pregnant. I havent even had a period sence then. I had maybe 4 or5 because my doctor perscribed clomid to get my period but never get one after that. my last period was on the 4th of March 2010. We tried to concive after that so i dont know if it worked. On the 30th and on the 31st i was cramping as if i was going to start my period. I was getting happy if i was because that means my period regulated. Now on the 1st of April i woke up dizzy and still came to work. My cramps continued and i went to the restroom. When i wipped there was a light pinkish color, so i was sure i started my period. I left work because i was feeling very dizzy and the cramps were still there but not bad. 20 mins later I got home and went to the restroom again to put on a pad, but only there was nothing on my underwear, just when i wiped. so i wiped a few times and after that nothing. ever sence then i have not spotted or did not get my period, but still have felt dizzy and cramping and very tired. Now my question is... Was that Implantation Bleeding or could that have been somthing else? I am now 4 days late for my period and tested for pregnancy 2 time and it was negative. do you think i could be pregnant but it was to early to test? Please help me answer this question i really need to know !!!