I had gallstone that dissolved with my stomach acid in a few months. Is this right?

Not likely. Gallstones usually are in the gallbladder, and are not exposed to stomach acid. If a gallstone made its way out of the gallbladder and into the intestine, and there is no sign of blockage from the stone, it likely passed out of your body through the stool.
No. Gall stones are made in the gall bladder which does not have stomach acid. The stone may have passed out of the gall bladder to the GI tract (without getting stuck in the duct), .