If you don't use intuitive F2L, learn that. If you do, lookahead. Practising slow solves helps a lot; one-handed solving forces you to turn slow but you may use more rotations. 4x4 also forces slower turning, but really, just try to do slow-turning F2L on 3x3. I sometimes do slow turning F2L and fast LL, which I find helps. Practise that, try to reduce cross to F2L transition (something which I should be doing...) and try to find good algs. But you're already doing well; it took me a lot longer than just 3 months to get sub-30. iirc, after the one month it took me to solve a cube, it was another 5 months before I was averaging sub-30. (EDIT: And try Roux or ZZ; they're also good methods. Roux for two-handed and ZZ for one-handed. CFOP is also good (although imo not as good, but still very good) for both, and if you want to stay using CFOP, try colour neutrality)
It won't take that much off your time if you can do 2-look OLL well. Plus, it isn't very useful for most methods other than CFOP. However, if you think you're going to stay using CFOP (remember to try other methods first), then you should definitely learn OLL. Half the cases are easy; I know 31/57 OLLs and I've never even really tried learning full OLL. If you have 5 minutes, just go to the OLL page on the wiki or on algdb.net (they're also useful websites to find better PLLs), and look for an alg that's 6-8 moves, maybe 9-11 if it's similar to something you already know, and learn that. It shouldn't even take 5 minutes for each alg. Also, look for ones with easy patterns to remember, even if it is kinda long. Doing this, you could probably learn 40 OLLs in a month or two.
