Period is late but I’m not sure if I should worry yet

Hello!

In the past I have had kinda irregular periods but the last 6 months or so have been pretty consistent, plus my bf and I have regular sex so I’m more paranoid lately. We use condoms.

My average cycle length according to this app is 32 days. Looking back the last 10 months my longest cycle was 41 days. I think we may have conceived on day 17 of my cycle but we have not had sex without a condom (worried about failure or user error here).

Currently On cycle day 37. Bought but haven’t taken a test yet. Haven’t taken plan B.

No other symptoms except some really bad stomach aches and diarrhea. What do you think? HELP!