Well ..... I tried two "weight calculators" for a Bass of those dimensions and one (Fla) said 6.5lbs and the other (Bass Resource) said 7.5lbs (which is what I expected from those guesstimators )
But, I have a LMG on the wall with dimensions of 22" long & 18" girth ... and it weighed 7lbs ... so I'd ballpark your fish at around the 7lb mark. Close enough for a un-weighed & released fish.
congrats ... that's a nice'un, regardless of any "exact" weight !!
... cp