Your signature indicates that you play five characters. Sheik is the worst of those five against IC's by a substantial margin so you should probably play any of the other ones.
If you must play Sheik, needle platform camping is effective only if you can shield drop. Fair on IC shield is good. Ftilt on IC shield is decent, since it tends to snipe all of their out of shield options. If you read an IC wavedash with ftilt you get a lot.
Practice combo'ing and killing Nana a lot so that when they come towards you you can launch them and easily kill Nana. Make sure your reward for hitting IC's is killing Nana, and the punish game will start to feel a lot less skewed. At that point you don't have to never ever get grabbed, you just have to win neutral a little more often than they do (it's not that much worse than other matchups).