More weight is probably worth a try if you already launch it high, as it might give you a little less hand action. You could also try to learn better technique; your numbers are pretty good aside from spin and you could probably gain 20 yards or more if you can get down to the high 2000s or so. You don't necessarily need to go with a particular flex as most heavier shafts will play tighter and a bit lower than light ones.
Your main enemy is your spin loft, which can be changed by fixing your equipment, but technique plays the biggest role in it. 3900 spin with an 8 degree head and 104 ss is a bit drastic. A better fitting shaft will help but you'll hit it even farther if you can get the spin loft lower with the same launch angle. Less spin loft should also get the ball speed a bit higher (a max of about 6mph and around ) without needing more swing speed. If you can drop 1000rpms and get your ball speed to 155ish, you can expect 20 yards of carry if you maintain the good launch angle. I'd say about when you get to 250 carry that's about as good as you can expect to get for fitting and you'd need really good numbers to achieve that consistently.
Static loft: The actual angle of the club, not necessarily what's stamped on the sole. There's also more loft high on the face and less lower because of bulge and roll, so hitting it high on the face can result in a higher than normal launch (but most drivers spin less there) and vice versa.
Dynamic loft: This takes into account the shaft lean towards or away from the target, so your 8 degree with 2 degrees of lean away from the target will present the same number on this stat as a neutral 10 degree head or a 12 degree delofted by 2 degrees. This is not exactly the same as the launch angle though.
Spin loft: This takes into account your angle of attack, and is the most important number for getting ball speed and spin maxed out. You want this to be low and you want to still be hitting up with the driver to increase launch. For a wedge or something to max out spin, or to get a controlled iron, you might want to hit down with a high lofted club to get more of a glancing blow, but with the driver you want
The problem most players have is that they try to launch it high and flip their hands to do so. This creates a good positive angle of attack, which is fantastic. But the problem is it adds enough dynamic loft from the forward shaft lean that your spin can be so high that you lose yardage. You want something in the neighborhood of 10 unless you're a long driver or really short.
As for shaft recommendations, the AXE series is supposed to be really good and stable for under 50$. You can also look at something in the project x line for a bit more coin or check ebay for cheap deals. Personally I think my fubuki alpha does an admirable job considering it's an S flex and I'm 15mph faster than it's intended to be swung. But that's like a 300 dollar shaft like so many of them.