I was prescribed Differins for the first time around 2001. After reading up about it and seeing that there was chance for acne to get worse before better, I became apprehensive about using it and therefore, did not. Then, many years later, I found myself back in the derms office, utterly frustrated with my skin. She ended up prescribing me Differins Cream. With reluctance, I decided to try it. I was relieved to find it did not make my skin worse, from an acne standpoint, my skin did become a bit more sensitive, however. After years of using it, I'm regretful I didn't start sooner.
So, although I was not in the same boat as you in terms of my acne having gotten worse with use, I can say that with much experience (and research; I'm 29 now), that you should do whatever it takes to remain patient with the Differin. If you read the leaflet that comes with it, it can take a few months before there's noteable improvement. I know this sounds discouraging, but your choices are to not use it and have acne or to use it and have acne with the possibility of controlling it and seeing yourself 3 months from now with much better skin.
Also, I would recommend using it once per day; at night time. Retinoids make skin photosensitive, so using it during the day when you will get sun exposure- whether direct or indirect, will only increase chances of irritating your skin. Using it at nighttime alone, however, does not mean you are OK to be in the sun the next day; you're still photosensitive, just less so. So use it once a day at night and only wash your face with a really gentle cleanser, like cetaphil, and apply a sunscreen/block! This is a good idea whether on Differins or not. :)
Lastly, with all of my research, acne is in part difficult to control because everyone is different and different bodies/chemistries respond differently to different forms of treatment. So unfortunately, treating acne can be a bit of trial and error, but it is important to give treatments a fair shake and not be shy about talking to dermatologist- bug them, they're paid a lot :)