Are all fruit & veg good for you,

Some foods can cause bloating. From WebMD:

Difficult-to-digest foods can cause gassiness and bloating. These are some familiar culprits.

Beans and lentils contain indigestible sugars called oligosaccharides. These sugars must be broken down by bacteria in the intestines.
Fruits and vegetables such as Brussels sprouts, cabbage, cauliflower, carrots, prunes, apricots. These contain sugars and starches that may cause gassiness and bloating.
Sweeteners can also cause gas and bloating. Sorbitol, an artificial sweetener, can’t be digested. Fructose, a natural sugar added to many processed foods, is difficult for many people to digest. To avoid bloating, be aware of these sweeteners in the foods you eat and limit the amount you consume.
Dairy products can be a source of intestinal distress and bloating if you have trouble digesting lactose, or milk sugar.
Whole grains, recommended for their many health benefits, can sometimes cause bloating and gas problems. One reason whole grains are so healthy is their high fiber content. But fiber is an indigestible carbohydrate. Abruptly increasing the amount of fiber you eat can cause gas, bloating, and constipation. Nutritionists recommend slowly increasing the fiber in your diet to allow your body time to adjust. At the same time, drink plenty of water with high-fiber foods, says nutritionist Joanne L. Slavin, PhD, RD, professor of food science and nutrition at the University of Minnesota. “All fiber absorbs water,” she explains. Drinking liquids helps fiber move through the digestive system and prevents bloating and constipation.

http://www.webmd.com/digestive-disorders/diarrhea-10/bloated-bloating

My trainer suggested that I eat the sweet fruits in the morning and not after lunch just because of the natural sugars.

Your trainer must be a genius.

All things in moderation. I try to steer clear of carb-heavy fruits (though I do love half a banana from time to time), but I can usually eat most vegetables (potatoes are a carb in my mind) until I'm stuffed without having any problems.