If you want to know what to improve on, link us to full matches.
I did watch one of the matches with you vs a fox.
don't roll nearly as much as you do. Rolling isn't good. Instead do a spaced attack or wavedash/grab or something, just not roll. It doesn't do much most of the time.
Against the fox, if they are off the edge, you just need to hit them with downsmash(if they are in range of course). It will knock them back pretty far, and you can either edgehog or downsmash again.
Don't use forward throw. Downthrow is the best throw 90% of the time. I occasionally use back throw to get them off the edge, then edgeguard with needles and downsmash. I love edgeguarding fox.
Now, if you are going to throw a single needle, just tap B. It's faster. And only I can throw single needles anyways.
Some of your combos you did down tilt, then forward tilt(the fox was at high percent). If you can end a combo with fair, then you definitely should, as long as it will kill or make for a good edgeguard opportunity.
You can get better. After all, sheik takes no skill and anyone can be good, no matter what you do. Always keep that in mind.