There are only some general rules about what is healthy. Healthy food helps you to be "in optimal condition". If veggies and fruits causes so much gas, you should consider to limit them somewhat. Exaggerating with fruits and veggies is not healthy any more. Also, not all veggies and fruits yield the same amount of gas.
Gas is produced by intestinal bacteria, when they break down fibers or simple sugars. So, veegies with a lot of fibers (beans, corn) or sweet fruits can contribute to the gas the most.
Also, raw veggies are by far one of the most difficult foods for our bodies to digest. Do you have the same reaction if they are cooked? Also, if you are eating a lot of carbs with your meals, ultimately, the breakdown of carbs causes a lot of gas.
No, I can boil veggies until they have no taste (about 40 min) and no gas. So the more they boil the better they are. Has to boil not microwave since boiling removes the color and what ever is causing my gas. I can microwave for a long time and still get gas. I also do a drain and refill on the water when boiling thinking I am boiling out what causes gas and draining it out. Some veggies cause so much gas I will be burping up mouth fulls of vomit until the gas is far enough down to come out the other end if I am constipated. Raw is much worst. Yet stuff like carrots and spinach have no affect on me at all.
If you burp a lot, have you had a test for H. pylori. H. pylori bacteria in the stomach eat some carbohydrates and produce gas.