BC pill skipped period

  HI
  I recently skipped a period taking Demulen 1/35-28.  I did begin my cycle yesterday with extremely light spotting. Two pregnancy tests say I am not pregnant, but having been on 3 rounds of antibiotics I am still concerned.
  I really do not want to consider pregnancy at this time for I have been on several percriptions in the past three months.  It is normal for flow to be light on the pill however is it common not to have a period at all?  Thanks for you time.

[hfhs.rn.bp]

Hi,  It is not uncommon for some women to experience very light (spotting) or no bleeding on the birth control pill.  It would be a concern if you had missed pills during the cycle. A change in your birth control prescription may be able to increase the flow if this is a concern to  you. Two pregnancy tests done a week apart are reliable for establishing that you are not pregnant.  If you are concerned about being on antibiotics and taking the pill, there seems to be conflicting information about pills and their effect  with antibiotics. Unexpected breakthrough bleeding or spotting can be a sign of an interaction with medication.. No withdrawal bleeding may be due to an interaction with medication which may decrease the estrogen stimulation to the lining of the uterus. To be on the safe side while you are taking antibiotics, you may want to use condoms as an additional back up.  You may talk to your provider about the possible effects of the prescription with your birth control pills before you start taking the medication.
This information is provided for general medical education pupposes only.  Please consult your physician for diagnostic and treatment options pertaining to your specific medical condition.