Over Use of Topical Acne creams.

Hi everyone, I just need some quick advice on somethings that's been bugging me for a while. About 4 years ago I started getting fairly moderate acne. I was put on tetracycline as well as Differin cream in the morning and Clindoxyl cream at night. Up to this point I've been using the creams everyday however I haven't been taking the pills for around 2 years. I haven't been back to my dermatologist to refill the cream in about a year as Ive just gone to my regular doctor.

My question is, will the overuse of these creams, or the prolonged use of them lead to serious problems down the road? Or will my skin only become immune to it? My acne is very controlled right now, maybe it's working like a placebo affect and has already lost its touch? I just want to stop these creams, get off any medication and FINALLY beat this. I feel that I've got the acne down to its last bit of strength and I want it gone. Any help would be great. Also, Could my skin possibly become dependent on these creams/gels. Thanks