Good luck with GP! ( I avoid mine at all costs too!! Have to be really really sick to go there.)
It does sound like cystitis. I suffer repeatedly from that. GP said its just unfortunate that some women are more prone than others, and because of our biological make up, its a wonder more women dont get it!
As far as CD goes, whatever it takes to get rid of the infection MUST be done. I often need anti-bi's for it, as self help stuff doesnt always work. I use bicarb, cranberry juice and drinks gallons of water to flush it through. Its utterly miserable so if GP suggests treatment - use it!! (Last time I had blood in my wee, that was agony. You dont want to lead to that, trust me!)
Goos luck!