You might be surprised.
7g is just 1/4 ounce. GH is right. You can lighten the heavy side, then use less weight on the light side. Your weight difference most probably is due to variation in the balsa density. 1/4 ounce could easily be due to this issue.
Correct one thing at a time. Get that right. Then see what else can be done.
Please let us know how it goes!
I'd be happy to trim it for you, but you'd have to send it to me.
Good Luck!
Allen