Freaking out! 6 1/2 months PP.

My partner and I have been using condoms as contraception. We have been lazy and sometimes been pulling out. I’m unable to take the mini pill because of the hormones, my body does not do well with contraception for anyone thinking why aren’t I on something. My son is 6 1/2 months old. Yesterday my hubby and I were having sex and he didn’t pull out! It’s the first time he has done so but I am freaking out. I wasn’t able to take “plan B” because the chemist said I would have to stop nursing for up to 10 hours! My son does not take bottles (we have tried more beyond belief) so not nursing for 10 hours is not realistic. Therefore I wasn’t able to take plan B. I’ve been getting my periods the same date but every second month since giving birth. I know they say all it takes is 1 time, but surely it will be okay. Any mums similiar? What was the outcome? Could I get pregnant off this? My last period was 18th of November. This mumma is stressed 😳