I don't think that your sides are bad, you have just a very strong front. I have a similiar situation (but more "skin" around my soulpatch) with a dominat front and grew everything out some time ago - not long, trimmed at 9 mm - with a better result than expected. In my opinion, it can look good if one has no big patches on the cheeks, but just less overall density on the sides. In fact, a lot of or even most guys have this growth pattern. Yet, unlike most others here who follow that "don't touch it at all approach" I would recommend you to trim everything with the highest possible setting at 2 weeks, again at 3 weeks (with the next higher setting) and so on... Growing things out this way, you will have a more tidy look and the difference between the stronger and faster growing front and the sides will be not so obvious. And slow growers have the possibility to catch up as well if you follow that "mehod". Good luck.