Anyone Bleed With Negative Urine Pregnancy Test, But Still End Up Being Pregnant?

I’ve just recently started fearing that I may be pregnant, and I was wondering if someone could give me a little advice. This is my first time posting, so please be kind. My ex and I last had unprotected sex on 05/29, and my period was supposed to start on 06/03, but it was 2 days late. I didn’t think much of it because my period does come late sometimes. However, my next cycle was also 2 days late, and I was lightly bleeding the whole first day. My normal cycle I spot, not lightly bleed, but after a couple of hours I get super heavy with clots. Over the course of my cycle, my bleeding became a little heavier, but I didn’t fill a thin pad until several hours of wearing it, and I had little stringy clots. Which is a lot different from my normal cycle where I fill super heavy pads within four hours. I only cramped for a little while on the first day, and then nothing. I took a urine test using FMU on 07/04 and 07/14, but they were both negative immediately. So, I let go of the idea of being pregnant, and I thought my period was just wacky that cycle. However, on 07/20 I got bad heartburn, and I’ve never gotten heartburn my whole life. I let that go as well, but my period that came on 07/29 was also 2 days late. Same as last cycle, light for the entire first day. However, this time the day after my cycle ended I had pink spotting with cervical discharge. I began to cramp, not terribly, but very noticeably. I also have a second long sharp pain in my right hip that comes and goes with back pain. I’m wondering if I’m pregnant, or if I’m just looking too much into normal female cycle changes? I apologize for it being so long.