Is there an effective way to treat acne?

Hello. I have been stressed about adult acne for several years. I have visited dermatologists for treatment and tried every famous cosmetic product, but my skin keeps getting better for a while only to flare up again. Everything from tiny bumps to large pustules appears alternately, and I just sigh every time I look in the mirror. I adjust my diet and drink plenty of water, so I don't know why this is happening. I feel like I've tried everything that is supposed to be good, but I just feel exhausted.
How did others break this vicious cycle? I earnestly request your advice on any real tips or cost-effective acne treatments that have proven effective. I want to know if there is a surefire way to treat acne, even if it costs a lot. I want to experience the feeling of having clear skin again. Thank you for reading this long post.