Irregular periods since they started.

I am 18 now but have been getting irregular periods from the very first cycle (which was one month long) then for about one year it was regular then again irregularities surfaced , was on some medicine which resulted in a 2 month long period and anaemia then was on medicine which included birth control pills 0.5mg for about 2-3 years stopped the meds in beginning of lockdown coz I realized they weren't helping my condition, started working out at home which resulted in somewhat regular cycles now I don't exercise regularly and my period cycle is quite irregular like 45 day or 55 days 35 days, not on any meds, I don't have pcod and there are no cysts in my last ultrasound. Should I be taking any medicine for it or just focus on my lifestyle and fitness.