I have symptomatic gallstone. is that why i feel bloated & feel pressure under right rib.

Likely yes: As you say that you already know that you have symptomatic gallstones, that would be expected to mean upper abdominal and right upper abdominal bloating & pressure discomfort soon after eating, worse with eating fried, fatty or greasy foods. Sometimes also associated with nausea. Laparoscopic surgery to remove the gallbladder may help.

Probably: Your symptoms sound typical. In people who have gallbladder problems, they typically worsen until the gallbladder is removed.