Worried

Long story short I thought my pharmacy closed at 10pm but it closed at 9pm & I missed it. I was going out of town the next day so I wasn’t able to take my pills for 4 days. I got home & got my new pack & it’s now my 2nd day back on it and we had sex earlier today. We’re married so we don’t use protection, just my birth control. What are the chances of getting pregnant? Me & SO have 2 other kids so we wouldn’t mind getting pregnant again, but we wouldn’t mind if I wasn’t. Just wanted to know how likely it would be!