Am i pregnant?

Patient: I am currently on Leven (pill) and have been for a number of years, I have forgotton to take this every now and again but on the most i am pretty good with it.My last period ended on the 13 January.last week i had mild cramps on and off again (mostly when i lay down), accompanied by tiredness (nothing unusual) and some headaches. on the weekend i started to spot, nothing huge, just a small amount in my underwear and when i wipe. this spotting is mostly brown.Over christmas i forcefully skipped my period by not taking the white pills, and let my period come two weeks late. I am now due to get my next one on the 30th?Is this ovulation bleeding or implentation bleeding, or nothing to worry about at all.I also took a pregnancy test over the weekend and it returned a negative result.Your help is greatly appreciated.thankyou!!!