If you can get your hands on some powdered leaf and can stand to swallow multiple grams of plant powder then that would be your most consistent and financially friendly option. I'll admit it's pretty harsh trying to swallow 5+ grams of powdered kratom but it'll be cheaper then the capsules and will ensure that your body digests all the plant material.
I wouldn't trust any brands that don't list the strain of kratom, there are red, white, and green vein strains and are named by where they are cultivated, an example would be "Red Thai." Not to say that all brands that list these names are good but respectable distributors of kratom generally use this system.
If you don't get results immediately with powdered leaf don't give up, kratom is much less potent than heroin. With a habit like yours you might need quite a bit of kratom, possibly 6-10 grams, to get relief. This quote is for powdered or plain leaf kratom only, if you are using extracts they will have a greater and less predictable potency.
I'd start by finding out whether you have powdered/plain leaf kratom or a kratom extract. If you have plain leaf i'd start with 3 grams as a test dose to make sure you can tolerate it. If you can handle that dose and it doesn't give you relief step it up by a gram or two until you hit your desired dose. If you find that you have an extract then we can't help you on dosing instructions since we have no idea how potent the extract is.
Good luck