Bleeding while on Birth Control. Negative Pregnancy test. Could it be ectopic pregnancy?

[Healthconcern123]

I have been taking birth control Othro-Tri-cyclen for over 2 years. Ever since I got on birth control my period has been regular. For some reason this month I have my period twice. I had my regular period and then 1 week later I got my period again or at least I think it is my period. I have been bleeding for about 12 days. The bleeding is starting to become lighter but still have not stopped. This past Sunday was the last day of my active pills so I am expected to get my period in about three days. So technically I will have my period for about three weeks, that is if my period does come or if the bleeding doesn't stop. I took two home pregnancy test and took another urine test at the doctor's. It all came out negative. I discussed this problem with my doctor and she suggest that my hormone could be imbalanced or I may need to switch my pills.

I am still concerned to why my bleeding won't stop and why am I bleeding while I am on the active pills. Has this ever happened to anyone? If so, what was wrong?

I read online that if you have abnormal virginal bleeding it may be ectopic pregnancy. I also read that ectopic pregnancy sometimes doesn't get detected in urine pregnancy test so you may get a false negative. Is this true?
Do you think this can be an early sign of ectopic pregnancy?

I have been having very slight cramps. Yesterday my cramps got a little worse but today I am fine. My shoulder feels tight or funny but it doesn't not really hurt.

Has anyone who have an ectopic pregnancy get a negative pregnancy test or bleed before their expected period?

please help.