Read both the dillution and subbing sticky. You are about the same size I am. It could take you over 2 months to get clean. There's no guarantees. Try eating a high fiber diet with metamucil and exercise as much as you can. Stop exercising a couple days before the UA.
Subbing with synthetic urine is really your best bet. Never get urine out of a toilet.Its going to be too dilluted and will probably contain flouride which will show up as an adulterant.