Tampons- idk if they are supposed to hurt maybe a slight bit but mostly if it hurts rlly bad your doing it wrong i think- I’d wait a little bit before you start using tampons, pads are easier and don’t require you to keep track of time, which especially with ADHD can be hard to keep track, and you can get a rare infection if you leave them in for too long.
Cramps- Curl up in a ball, hot tea, heated stuffed animal or a hot water bottle, and a warm shower all help me, also he scent of lavender for some reason
Leaks- just change your underwear/pants if it gets on them, give them to your mom asap cuz blood can stain if you don’t take it out quick
Lower Back Cramps- I do get them a couple days before my period, but it can also be a sign that you’ve been sitting down for too long and if you lay down for a little bit, sort of wiggle and roll till it feels good, it should help.