Someone plz Help!!

AF lasts about 5-6 days, and I get them every month at the beginning of the month. April I got my AF approx 3rd to the 7th & this month I got AF 3rd to the 7th also. April is an approximate as I don't clearly remember, it started either between the 2nd and the 4th (not exactly sure). And I'm already confused explaining that lol. 
What I'm confused about is my luteal phase, my cycle length and all that jizz jazz, every app is telling me different, and most are saying I ovulated Tuesday and well no I didn't!
 I had stretchy clear CM Friday evening after intercourse, Sunday evening, after I inserted a finger to check CV it was also stretch clear CM and yesterday, Wednesday the 21st, my knickers had a lot of CM but when I wiped it was milky. When did I ovulate? How do I work all of this out please helppp!!! 
​I had intercourse the 16th, 17th & 18th all I basically want to know is did I do it to early? Is there still a chance of being pregnant?