Some thoughts:

1) Consider moving the First Aid items into another separate pocket sized first aid kit.
2) I was going to say what MH said about shelter but I see from your later post you have that covered. Not sure how that bag works but you might consider a poncho or garbage bag to cover you from the top as well (I assume by bag you mean a bivy type bag).
3) Fire seems to be well covered.
4) Water seems to be well covered, although Izzy beat me to the oven bag recommendation. Don't forget a zip tie to go with that. The metal cup would also be a good idea if you move up to a larger kit, but is not really practical for your pocket sized kit. Check out this older thread http://forums.equipped.org/ubbthreads.php?ubb=showflat&Number=190456#Post190456 for an alternative for a pocket sized kit.
5) Signaling seems well covered, although you could throw in a large brightly colored bandana (that can serve a multitude of other uses as well). Make that garbage bag or poncho brightly colored as well.
6) Food procurement is covered but like MH said an immediate energy type food in your pocket or pack shouldn't be overlooked.
7) A knife would be a great idea even with the scalpel as a backup. Just don't break any school rules or local laws carrying it. A wire saw might be useful as well. Don't forget extra batteries for the flashlight.
8) The duct tape and sewing kit are good multipurpose and repair items. If you wear glasses like I do a glasses repair kit would make another good addition. A few extra safety pins wouldn't hurt either.
9) How about adding two personal protection and comfort items: sunscreen and insect repellant. I think you can get small sizes of these suitable for a small kit. Some may not consider these necessary for a small kit but a sunburn or nasty bug bite could make a survival scenario miserable, even life threatening (think dehydration and increased temp that comes with a sunburn).
10) You mention a compass; a map wouldn't hurt (even a small one just showing the general lay of the land).
11) Update the contents list or create a new one as you have obviously added some extra items already and may end up adding a few more as well.
12) Everything I have seen on the PSP has mentioned only 3 sq ft of aluminum foil. I don't think that has changed. Can anyone else verify that?

As I recall you are still of school age and you mention you carry this kit without the shelter item at school. I feel this forum would do you a great disservice if this was not also mentioned: don't violate school rules with respect to knives and other sharp objects, specifically the scalpel, no matter how ludicrous and insane those rules may seem. A pair of scissors or EMT shears may be almost as useful and not raise any eyebrows like a knife would. One of our other forum members does this due to anti-knife laws in her community. Dagny maybe? Anyway, just thought I should point that out. Hope this helps.