According to my docs, your only meant to be on it for a maximum of 2 years. Because of the possible link with it causing brittle bones etc... They have told me I'm only allowed a couple more then they have to find an alternative ...
I'm going back onto the pill, they suggested the implant but my friends who have had that have all put on weight and onlylost it again when they had it removed so don't want to ruin my good work!