I'm about 8 weeks late?

Hey well I'm a little worried my lmp was 12/22-24/2010 I have not got my period since been having all the pre go symptom I have a 11/2 but keep getting neg hpt. I went to the er on 2/9/2011 because I been having a lot of back pain when I went they did a pre go test and it was positive they also did a blood and u/s but those came back neg. I had a hpt today and it had a faint line.. Can some one please how have been in the same boat please help... Thank u