Hopefully you didn't move your saddle forward to get closer to the bars. That is a no-no. If when the saddle is where your pedaling function preferences say it ought to be (that is a primary independent position factor), and the 90mm stem is still too long, I would say you should size down.

It would surely not be too expensive to pick up a 54 cm frame and just move all your parts over to it. Frames are easier to buy and sell than bike, because they are so much simpler. Less details for the buyer (including you) to disapprove of. You could get on ebay and pick up something used. Maybe even an upgrade over what you have now. The deals are great. Or a no-name carbon frame for a few hundred bucks. Much cheaper than a new bike, even probably if you could sell your old one.

But be sure you want a 54. Is a pro fit in order?