What I can say, without any doubt at all, is that I've read enough evidence in your post to say you could be doing a LOT better. I've been well into maximising my distance for my swing speed for about two years now and read quite a bit and have downloaded charts relating to this topic.
I started a post on here about hitting the ball too high, wondering if I could drop down from HT (13) to 12 or maybe even 11 degrees, but there is a limit how far you can get the ball "out there" depending on clubhead speed.
There are 2 ways of looking at it. 1) the mathematical reasoning for choosing one loft over another and 2) the reality of how you hit the ball.
with 90 mph you can easily improve. Mathematically, a 12 degree is going to suit you very well, BUT (and this is the BIG question) if you are adding loft you might be OK with a little less loft.
However...in general, you need to be creating approx 14-15 degrees of dynamic loft to max out. I need to create nearer 16 to max out. I can get up to 230-240 with good roll (although not right now, got some issues) so you can easily get to 250. Sound good? - try more loft.
