scared and ashamed of myself...

I am 19, out of high school. Boyfriend is 18 still in high school. I was on birth control for 8 months but all for a sudden it wasn't working making me emotional, and have long painful periods with weird clots. So I stopped it. I decided to start taking myo inositol because I have pcos and it helps with cramps and regulates my period. Anyways I started charting and doing bbt to be extra safe. And for three months my temp dipped and then rose slowly indicating I ovulated after the dip. Well this time I ovulated on the dip. That's besides the point... We got high I wasn't thinking and I was extra horny (ovulation) this is no excuse I know I was being reckless and careless. Well.. I ovulated the day after having sex. I am so freaking scared I am not ready for a baby and it's too late for plan b. Idk what to do :( I am so so ashamed of myself. I feel like I betrayed my boyfriends trust because I was open and honest with him about my cycles. One time and one mistake is all it takes I guess.. Really hoping I don't get pregnant 😢