rumrunn6

I don't understand the sticker on this bike. it's a little round white sticker that reads: 18" but when I measure stuff, this is what I get

seat tube crank to top of tube 21"
standover 29"
top tube 22"

I'm 6' with an inseam of 34"
I was thinking I should have a bigger frame - I found this bike abandoned and have been using it off an on, but I mostly ride road bikes.
Should I be looking for a bigger frame?