Cousin said I should cut my hair short since it’s “too thin” to look nice long

Here is my hair length for reference. I am currently in the process of growing it out along with getting consistent trims to eventually cut out all the blonde (from previous hair dye). I have thin hair that becomes quite obvious when it’s greasy lol, but I think it looks healthy after a good hair care day!!

Is my cousin being dramatic, or should I cut my hair short to add more fullness and volume? I know it is ultimately my decision either way, but I wanted opinions on this because it’s true, I’ve seen such gorgeous long hair come from people who have a lot of it. But guys, I’m tired of the short hair 😂 lmk if I’m crazy or if she’s trynna make me lose my growth process lol.