Weird periods and on birthcontrol for 6 months now.

I have been off birthcontrol for about 6 months now if not longer, my periods were pretty regular soon after. My periods have ALWAYS been regular, no missed etc before birthcontrol. In september, I was due for a period around September 2nd, and ceased to get it until September 26(it was a normal one meaning no change in flow or # of days) but it was way late than what Im used too. Well I got my period again around October 12th, and I feel like it was very strange as it seemed to early for another one. It didnt even give me clues I was going to start like it normally does(sore breasts, cramps) and was way longer than usual. It was kind of like just spotting for 2 days, really heavy for several days, than back to spotting for a couple more days. I know irregular periods have alot to do with stress, but I have had bad anxiety for several years now, so Im always under stress and it has never effected me. So I dont know if it would now, or its something else. I did have unprotected sex on the 3rd, and the 11th but I dont think it would be effecting my periods now. I had went to my Doctor about my late period but they convinced me that I shouldnt be worried about it. Am I reading too much into things, or what do you think?

Any thoughts, comments, opinions will be welcomed.