Very confused… please help

Hello, I am 20 years old. For some context, my periods have always been extremely regular. I get them exactly every 5 weeks, no cramps, no issues (I know five weeks is long but I have always been this way). I have always had very healthy and normal hormone levels, minimal PMS symptoms except for mild breast pain a week before my period starts. For some reason I have not gotten my period in 7 weeks and I feel extremely off. For the past few days I wake up with lower abdominal pain, I have had breast pain for the last 2 weeks, constant mild headache, constipation and fatigue. I am sexually active with my partner but I use natural birth control by following my cycle and it’s worked for two years (this has been easy for me considering my periods are normally very regular). I did a pregnancy test a week ago and another one two days ago, and both had a negative result. In terms of medical history, I do suffer with severe mental health issues and take five medications prescribed by my psychiatrist. I have been on these for a number of years, except for Vyvanse which I started a few months ago (switched from Ritalin to Vyvanse). Once a year he makes me do a blood test to check my thyroid, liver, iron, essential vitamins and few other things. The only issues I have had are iron and vitamin D levels that are in the normal range but on the lower side. Once again, these small issues have never caused me problems. My last blood test was around three months ago and everything was normal. No diet changes or weight changes, although I have been