HOW DO I NAME MYSELF?!

I’ve known I’m trans for a long time. I’ve struggled with what to call myself for so long, and sadly I can’t just ask my mother to rename me, I’ve gone through -Rayne (stoped using bc wtf was I thinking?) -Merlin (love but super clocky) And now -Malachi But usually after 5-6 months I feel like it doesn’t work/fit, how do I pick a name? I’m 17 and I feel like I’ve got to decide soon, idk. I’m not sure if Malachi fits me, I’ve thought Oliver because I’ve always loved that name. How do I know if it fits me and I won’t regret it later?

Edit: I already chose my middle name Jakob (after my brother in law who was the only one I really see as my brother) so my full name would be (Malachi/Oliver ext) Jakob B