Oh gee, tough break to be without a job and insurance!
Basically, I'd follow the instructions on the bottle/package, and adjust to what works for you.
Couple of things though. I'd go with the pills over the liquid or chewable to avoid getting a black tongue. Also, once you figure out what your total daily dose should be, try to space it out evenly throughout the day, so the level is more or less constant. The instructions are more for acute diarrhea and tell you to take it after loose stools. Those instructions assume you have a colon.
To save money, buy the generic bismuth subsalicylate. No need to buy the Pepto Bismol brand.
One minor caution. Don't go crazy with huge doses, particularly if you are going to take this long term. There have been rare cases of encephalopathy caused by bismuth heavy metal poisoning (seen in the elderly on megadoses). Not likely to happen to you, but just in case you have kidney damage or something to prevent clearance of the drug, you need to know there can be a downside.
You can also try various probiotics to help keep the ad bacteria in check.
Hope it works for you!
Jan