Like others have stated, you learn to adapt, and typically find that while ambi controls are nice, they're not an absolute necessity. There's certainly no need to give up left-handed shooting.
That said, I'd recommend a revolver.
IMO lefties actually have a slight advantage using a revolver that has a counter-clockwise cylinder rotation, like the S&W's. Because the cylinder rotates contrary to the strong side of your grip. So if your adversary grips the revolver over the top strap in a manner that stops the cylinder rotation, you have the advantage of being able to roll the revolver inward, forcing the cylinder to advance. Try this with an unloaded revolver some time. It's very hard for a righty too keep the cylinder from advancing against a lefty.