As Alan mentioned above, I'd think about packing a small blade even a box cutter or X-Acto blade. While speaking of blades, if you don't have a multi-tool with a saw blade, you can also cut a thin hack saw blade to fit in your kit. You can never have too many blades.

He also mentioned the Gerber Seal N Go Breast Milk Storage Bags. These are great for taking little space when empty and yet holding water quite well when full. Doug did a write-up on them on the ETS site.

I used to carry zip-ties, but decided to switch them out for Jute Cordage. The reason I did this was that Jute can double for tinder in a pinch. It isn't a substitute for carrying a good length of 550 paracord of course (which you've listed anyway), but sometimes you just need a little string for smaller jobs or tinder.

I'd probably switch out the iodine tablets for some Katadyn MP1 tablets.

You could wrap the kit in some duct tape before you wind on the 550 as someone mentioned previously, and could cut up a bicycle innertube and add some ranger bands around the kit as well. Ranger Bands are handy for securing things and as a fire making aid as well.

In a lot of my medium PSKs I pack a slingshot band. I don't know if you have room for one, but it's a worthwhile item if you do.

Welcome to the forums!