Hi Juliana,
Middling male from Blighty here.Well done on your good lifestyle.
From the stats I`ve seen,97% of US soy is GM and some of the organic labelled product is not organic at all.
You are getting a lot of sugar from the fruit juices,maybe too much.Any chance of ramping up the leafy green salads....those you like the taste of,perhaps adding organic lemon or lime juice.Maybe try some mixed veg&herb drinks as in Rabenhorst etc.Do you get along with beetroot juice....as used by Olympic competitors?
Is your meat free of antibiotics/growth hormones and not grain-fed?Maybe try grass-fed meat and eggs from pasture raised hens ,if you`re stuck on animal products.Perhaps improve your prebiotics(oat brans etc,which feed the probiotics) Most of the probiotic stuff on the shelves,incl Hellthfood(sic) Stores,is next to/completely useless ,tests show...I have carried out such tests.Build the friendly gut bacteria up yourself.Avoid synthetic vits and any supplements with dodgy fillers/additives.Have you consumed any Big Pharma products deleterious to gut bacteria besides Aspirin?Any chance of using natural pain control remedies?Around 70% of your immune system lies in your gut?
What bread do you eat,do you know the ingredients?Most shop bread is made from highly denatured materials,some of the additives in bakery products interfere with stomach acid ,levels of which should normally be very good in a young person like yourself.Do you consume products where the yeast is of the incompatible type and still live?No history of Candida following antibiotic use?Sugars in certain fruits/fruit juices could feed thisHave you tried organic sourdough breads such as Spelt?
Water:Drinking large quantities,especially in one go can not just be a strain on the stomach but can in fact be harmful(as ex-F1 driver Mark Webber and other people have found to their cost....some even fatally).
If comfortable for you,couple of glasses of warm water on rising to get the organs active and the stomach ready to accept food,but give it 20 mins-half hour before consuming any solids.Drink lightly,albeit often or sip regularly between meals ,but 15-20 mins before lunch and early evening meal stimulate your stomach acids with a glass of water(not cold) ...it doubles a particular digestive component in the stomach.Don`t drink with meals,you don`t actually want food in your stomach for that long and gentle upright exercise will aid digestion.Remember to chew food well whilst sitting upright and relaxed.The food will be quickly turned to chyme in your stomach and pass to your duodenum,the start of your small intestines,from where the pancreas and gall bladder will introduce further digestive components.Don`t drink for an hour after meals,let your food digest properly during its relatively long journey through the various sections of your small intestine.Remember the stomach is placed high up in the abdomen ,adjacent to the heart(hence heartburn)and expands to accept food but contracts once it`s passed the chyme on.Your "distention" sounds like small intestines,it wont be your stomach.
Following the advent of MOOCs,one can do free quick courses on the abdomen etc,which could be helpful as they cover muscle structure as well as digestive tract.
As for exercise,I would recommend The Bridge and further exercise extensions thereof.Not good to do heavy or prostrate exercise just before or after eating and avoid that sloshing liquid in the gut situation I alluded to earlier.Have a break from the fruit juices and see how you go.Do you eat Avocados....great food but don`t overdo them.
Beware of the Alkaline Myth doing the rounds,have seen people get ill on that lie.
Hope some of the above is useful to you.We`re all different......one man`s meat is another`s poison,as they say.Different blood types,metabolisms,predispositions Once you find the food/drink causing the bloating,perhaps through an elimination practice,hopefully you`ll be fine.
The bloated tummy look seen in some pics of African malnourished infants is due oftentimes to intestinal parasites.A handful of fresh organic pumpkin seeds daily can do the trick,as well as supply zinc,the body`s traffic cop! Wouldn`t recommend daily consumption of large amounts under normal circumstances.One doesn`t have to have spent time in the tropics as I have, to fall foul of worms!You can get them in any climate.My father worked in what was then Persia and was sat next to a chap eating pork and he politely pointed out to him that there was a worm wriggling around in that piece of dead pig 
Mind how you go
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