Why is my period late?

My period is always on time every month, never late. This month I haven't got it. My last period was April 23rd. Only lasted for 3 days. A little over a week ago, I had a couple tiny drops of blood on my underwear after me & my man had sex. No blood on him, just my underwear. I wiped after & nothing whatsoever. Thought it was weird & my period starting but it wasn't. Guessed it was implantation bleeding but not sure. Around when that happened too before I bled, my nipples were on FIRE. I ended up putting cream on them. They only start burning when I take a shower. They been burning ever since till now but not as bad as that day. They were burning so bad, I had to breathe in from my nose & out of my mouth to breathe through the pain from my nipples. They never EVER hurt or burn like that. Even before I start my period they don't burn how they do now & they only will be a little sore for a couple days then I get my period a couple days later. I also been cramping for the past couple weeks & got sharp pulling light pains on my left side that only lasted a couple days then pretty much went away. It says on my period apps, one of them says I'm 14 days late, the other says I'm 19 days late & another says I'm 10 days late. I have been taking pregnancy tests but every one of them says negative. Me & my man been trying for a baby but we haven't been overthinking & thinking about it too much so we just tell each other when the time comes & if it happens then it happens. 🙏🏻👩🏻‍🍼👶🏻

If I am pregnant, would that mean I ovulated later & that's why I'm getting negatives right now? I don't know. Just very frustrated that my period hasn't shown up with negative tests & on why I been having cramps, burning nipples, & blood on my underwear that one day..

I am planning on going to the doctors if I don't get my period in a week or two but I am currently waiting for my insurance card.

Does anyone have an idea why maybe I'm late & all those weird symptoms I'm getting?