I've Had A History Of Problems With An Inconsistent Period,

I've had a history of problems with an inconsistent period, ovarian torsion, and ovarian cyst. I've had a pretty consistent period for the past year after going back on Ortho Tri-Cyclen. Then in September I had unprotected sex with my boyfriend when we were drunk, and realized the next day I had missed a pill at some point. So I panicked and went and took Plan B and got my period about a week late, but took a test and it was negative. Then we had unprotected sex again in November the second to last day of my period of that cycle. But had been prescribed amoxicillin a little more than a week before and so knowing the risk of that took plan b within 39 hours roughly. I also got the generic brand of Ortho Tri-Cyclen prescribed to me so I got it late when I was supposed to start my new pack the day of the unprotected sex. And didn't start it until two days after I took the Plan B. According to when I started my new pack I got my period on time it was just lighter than normal and a day shorter. I've nothing else off besides that so just want to know if there's still a chance I could be pregnant. Or if it's a combination of not only taking one but two plan b pills in the past three months, and starting my pack four days later than normal.