When do I know!?😩

I'm only 13. Ive had my period for a year and a half now... Which leaves me with a lot of irregular periods. Some months it's short like 2 days... And others I miss a whole two months and have a major period! Which leaves me wondering, when is it going to stop!? I hate it because when I go to sleep, I don't use a tampon, because fear of toxic shock. Me and my mum are very low on money, so I use a shit load of toilet paper for when I go to bed. (If you use heaps... It's just like a pad!)And in the morning... Tampon. But today I realised a lot of clots on tampon AND in the toilet, after that it stopped! I don't know when it's going to end or if I should put in a tampon just in case... But because I'm at school most of the time I don't get the opportunity to check if it HAS come back to bite me in the butt....
When is it going to end and how will I know!?!? I need someone's help, and soon! Thank you guys!!!!!