I've got a couple of videos from this weekend.
http://www.youtube.com/watch?v=fi0Gp8VEqJ0
http://www.youtube.com/watch?v=6Tr1amO5ApM
http://www.youtube.com/watch?v=PA7ZKQ1KROs
These are all friendlies, none of my tournament videos were recorded. None of these really illustrate the CCing issue I've been facing, since this opponent didn't do it very much, but regardless I think these show me playing at my best. Please excuse the hiss, my recorder decided to record all the matches at super low volume, and I hat to do magic to make it audible.
I'd say some things to work on would be using less DAir, especially against a fast character like Fox who can be annoying to punish.
Also, some work on the ledge game might help too. Ledge hop UAir isn't exactly that threatening or safe of an option. Her WD from the ledge is really fast and mostly covered by invincibility frames if you can get the timing down. Maybe try to work on that if you've got some spare time.
I think you should also Dthrow more. Try to set up some more grabs and use needles more. Needles, in addition to doing damage, can help set up for some easy grabs. I saw a lot of upthrows in the second video. It's not bad against a fast-faller, but I think it's easier to chase off of the dthrow.
Another tech chase tip. I saw you predict/react to a tech in place and punish with Dsmash a couple times. Dsmash isn't bad if you're near a ledge and you're trying to get him off the stage for a gimp, but since you were in the middle of the stage, you could have tried upsmashing or regrabbing since they have a lot more potential for chaining into other moves.
Finally, a general gameplay tip would be to save your double jump, especially as Sheik. Since if you get knocked offstage without it, your recovery becomes extremely predictable and even more punishable than it already is. I think I saw you get punished for using it a few times when it wasn't needed.
Also, you mentioned getting CC'd a lot and it being tough to deal with. Tech chasing/chain grabbing the low %'s with dthrow solves most of the problem depending on what you're playing against. I know that's a pretty gay strat for friendlies though.