The racquet is not the issue here, if you had a small head 85-90" 18x20 with syth strings, something more open and larger would assist. The 5g should generate enough spin, as long as you can handle the mass (high head speed) a heavier racquet will generate more spin. It's not easy to generate spin with an Eastern grip, obviously it can be done hence Federer's dominance but it's harder than a semi-western. If you are hitting flat then it does not matter what racquet you use, you wont get spin. Try a Semi-Western for a week see if you can generate more spin and hit harder first.
I'm thinking about going to something like what your currently hitting with. I current use a Redondo 98 with about 17-18g of lead at top handle, but I'm starting to struggle to recoup between matches and I've worn through the head after a few scraps across the back fence and half volleys. I used to hit with a 5g PSE and always felt fresher afterwards but I'm aging and it's not just the arm that needs more rest the legs are struggling.
Post a forehand & backhand video. If you hit flat and don't want to change then you need a low powered racquet as you won't be using top spin to assist bringing the ball down. Pin point placement will be your weapon.