My last period begun Nov 5, 2017.
I've used a period/ovulation tracking app for the last 9 months. My shortest cycle was 29 days. My longest cycle was 34 days. Thus my average cycle is 31-32 days.
According to the app my ovulation date was estimated Nov 23 with medium to high fertility during that week Nov 18-24. No contact whatsoever during this time.
I had unprotected sex on Nov 30 (1 week after ovulation -- app says low fertility). My partner says he didn't ejaculate inside but only outside.
I was expecting my period this month last Thursday Dec 7, 2017. It's Monday Dec 11 over here supposedly my fifth day but still no sign of menstruation yet.
I have taken 2 home pregnancy tests. One last night but my urine was more diluted. Second this morning on my first pee better concentrated. Both came out negative.
I thought I would have finally rested my worries after my negative results but maybe I still need more assurance from real more experienced women. I'm avoiding pregnancy.
I have never taken birth control pills previously and have no known relevant medical condition.
With all information above, how likely am I to be pregnant? Could I have ovulated late? Could I be pregnant in any other way? Am I stressing this out just a little too much?
If I'm not pregnant, what could have caused my delayed period?
Thank you for your help.
I'm 19.