I am a 27 yearold female.I have never been on birth control,But I have never been preganant either.I missed my period in dec 07>I had it in the first week of jan 08 and bleed until the frist week of feb 08.I have not had my period since and it is the middle of march.I am pretty concerned.If anyone has any answers please let me know.thanks for your time.

I would highly suggest you make an appointment to see your gynecologist. That's not normal at all.

I am having similar problems for past like 6 months. In the fall, week late for my period, finally got it, but like 3 days after my period ended, I started bleeding again for like 4 more days! It happened for a second time so I went to the gyno for the first time (had pap smear and cultures done).Had hardest time getting my results (just found out yesterday both were negative). Now AGAIN I am like 5 days late for my period set up appmn't yesterday for this Monday and hopefully see what's wrong. Tjinking she might suggest birth control but I'm not sure which one to go with? There might also be a different problem though... si I don't know. Just sharing my experience

I agree that it's time to see a doctor. There could be lots of reasons for this, and only a doctor can tell you for sure.
This link has some info on irregular periods:

Missed or Irregular Periods - WebMD

Hope everything is OK!