15 days late!?

Georgia • 20 years old, married military wife 🇬🇧🇬🇧

So, I took a pregnancy test when I was a week late, had a vvvvf line on a blue dye test.. so I waited a few more days and took 2 pink dye tests and they were negative so I'm just assuming I'm not pregnant.. can't understand why I'm so late!!😩😩 I'm getting so bloated and cramping as if I'm about to start my period and I just don't come on?? Any advice?☹️☹️