based on your height I would estimate you'd fit a 19-21" frame, current bike is too small.

Look up 'soma sparrow' handlebars, mount those on a 150mm+ stem down low. Will let you get lower for speed, but still have good control. Also will let your current brake levers/shifters directly transfer over, possibly without needing to recable. Should you change over to a road bike in the future will also mount road levers.