hair loss

So I'm 26. I don't dye my hair often. But even before I've ever dyed my hair. I would lose a good amount of hair every time I shower. Does anyone know of anything that will help my hair fall out less???  I've never had thick hair nor a lot of hair. But I would love to keep the hair I do have. Lol. And if that maybe make it fuller if possible. But main thing I don't want to lose so much 😩😩😩 help anyone. Advice. Something that actually works.