L.M.
wow sounds like me at that age, only I didn't get testing done...
The 1st year of my periods were just weird. 5 days to 35 days long, super heavy and some that were just light pink water. I also got clots the size of DVDS. Weird stuff. I didn't tell my mom because she always told me all the crazy stories about her periods as a girl and my female cousins all had similar stories. I really thought all girls had it like this for the 1st year or so and didn't think it was worth telling to my mom.
It took a year do calm down and regulate itself. After that I was 7 days and always started on the full moon. I was so regular it was funny.