I'm just about your size - 5'0" 28.5" inseam. I ride a 44cm Ruby Pro, I even had to put a shorter stem on it - I think it came with a 90 and I went to an 80. A 48 would just be way too long for me. While it may afford you a bit more of an upright position, being stretched out on a larger frame will sap your power and cause you to have less control.... As you are used to riding a more upright bike it may take you some time to become used to the drop position, so don't give up on any bike you get right away.

If you can get a bike that has not already been assembled you may be able to get the shop to leave the steerer tube long and put extra spacers below your stem so that you can be up a bit higher - though Specialized has been putting some somewhat funky stem/handlebar combos on some of their bikes these days, so I'm not sure how that would work. You can also look into an angled stem. Mine is angled, though I put it in the down position, as I don't feel I have enough drop, rather than too much.....