unclench, you might implode if you tense up any more

So ... no pressure?

Go to the state fair.
Go attempt to get the big bear at the ring toss.
Fail.
Offer her a consolation prize of "Will you marry me".

Jim, my spotted brother from another mother.
First? BREATHE! Seriously, you look like you're gonna explode and implode at the same time.
Second, it's Jo. She's practically eloped with you. What you need to do to make it special? Wait till the two of you are having a warm happy snuggle session. Like on a couch in front of a fire, or just binging on movies. Might even be fun during a scary movie-thon.

Aaaaand most importantly. BE YOU! Don't complicate crap by trying to be extra. Jo's not in love with extra, she's in love with you

My dude, don't over think it. Just do it.