There are four occurrences of trills in this piece, all in the first movement, right? Also, which is your fingering for them?
I play all of them with 2-3 fingering and do the Nachschlag with 1-2.
What chopinlover01 said is true. Playing trills with 1-3 or even 1-2 for fingering provide a much stronger and accurate sound. In my opinion, 3-5 could be included in that. Personally I found 2-3 and, of course, 4-5 (by far 4-5) the hardest fingering for trills, but, of course, you can't use the same fingering in every section and every piece (that's the sad part of the story).
Choosing a fingering for a trill depends much of the keys you're working on (white-white, black-black, white-black, black-white), the interval between them (2nd minor or 2nd major) and the notes preceding and succeeding the two notes you're trilling. The fingering 1-3-2-3 is also useful when playing long trills, using the Alberti bass pattern (there's a specific name for this kind of trill, but I can't remember right now).
Well, in Op. 49/2, I recommend you trying 2-3 fingering and ending with 1-2 or maybe 1-3, in all the cases. I'm already used to 2-3 in this piece, that's why I say so, but you can try 1-3, which is easier, and do the Nachschlag with 2-3.
Usually to very short trills like these I find 2-3 actually easier than 1-3. In Op.49/2, in all the trills, the fingering 2-3 is going to be played no more than 3 times (like 2-3-2-3-2-3, ending with 2-1-2) (or 1-3-1-3-1-3 and 1-2-3), so you don't have to worry with hearing the trill for too long, but be sure to hear the auxiliary note at least 2 times.
Practicing trills is a matter of finding the way your fingers and forearm get in balance. Have your fingers close to the keys and hit them very briefly, like not pressing all the key down (it at least works for very short and light trills like these in Op.49/2).
Anyway, you'll get more results after you choose a fingering wherein you're confident and practice it a little slower than you want it to be.

Hope I helped.