I might be way off base here but I get the idea that you are hesitant to try more Liver Flushing and try some enema/ colonics. Just do it! No one will find out, and even if they do I wouldn't let what others think affect your decisions to cure something that is having such a negative affect on your life. Screw em. I was 18 not THAT long ago *lol* and know how taboo it was to even talk about things going in or out of my arse. I think you have to be more confident in yourself (screw what others think) and more aggressive in your treatment of this odor. All this stuff is very safe - read up on directions on CureZone and you'll get through any treatment just fine.
I'd do more Liver Flushing asap. Use a strainer, count your stones, keep records. Do at least 3 or 4 more flushes before you give up on them. Every 2 weeks is fine. More often is ok too if you feel up to it.
Do you have insurance to cover medical/ blood/ bacteria tests? Will your parents pay for it? Take advantage of it and see a doctor. Usually people with bo are referred to a Dermatologist, but your General Practitioner (family doctor) might be able to help. This will be harder to do in a few years when you are on your own and need health coverage. Tell him about your odor. He might find something wrong. One thing though - stay away from Antibiotics .
Splurge on the $70 or so to have a high colonic done. Do enemas at home. Try a salt water flush or two. Maybe even a master cleanse (although I don't know much about the master cleanse).
I stopped consuming dairy and Sugar and now follow a "caveman" diet. I consume mostly meats, fats, vegies, nuts, water. I'd say do the same - probably harder at your age to drop things like pizza and fast food though.
Probably more than you wanted to hear. I definitely had a positive change in social functioning when my body and breath odor disappeared. At your age you'd probably get even more benefit.