It sounds like you should have laser done on your back and trim the remainder of your body hair. The laser treatments can get expensive (maybe $400 to $800 for a full back). And if you decide to trim your body hair, make sure you get an adjustable trimmer so you can easily find a trim depth that makes you happy.
If you decide to wax your back, you could spend between $45 and $80 for a full back and it may only last 10 days to 2 weeks before the hair starts to show again. Waxing is done at most day spas.