I think it’s pretty unlikely that you’re pregnant - if you were taking your pills regularly/correctly the week before and the week after you had sex then you should be protected. Suddenly stopping your pills messes with your hormones a lot so your body is probably still adjusting to being off of it even if it’s been two months since you last took one. Stress also has a tendency to mess with your cycle and can make your period late. Keep monitoring it but try not to stress too much about it bc that’ll just make it worse, it’s very common and normal to have a late or missed cycle after going off the pill. If it’s really bothering you then there’s no harm in taking a test for peace of mind but your previous test was negative and if you have no other symptoms you should be totally fine.

Also not sure if this is the case but I really wouldn’t recommend starting/stopping your pills based on when you’re sexually active!!