There's nothing wrong with a 15 lb. base weight. I got mine down to 13 but then decided that this old lady wants more creature comforts. It's now back up to 14 and will probably stay that way.
It doesn't sound as though your baselayers are too much out of line. You can find lots of good stuff in the athletic departments (not sporting goods) of stores like Target, KMart and wallyworld that may or may not be lighter but at least won't break the bank. Always take your scales with you when gear shopping. (I always take my digital postage scale when I shop, to the horror of store clerks, especially at REI).
I'd concentrate on the items on which you can achieve the biggest weight savings. Obviously your jacket is one of these. If you shop around on the internet you can probably find considerable dollar savings on your Montbell Thermawrap. I was lucky enough to find a closeout color (actually, a quite pleasant brown, especially hard to find in women's wear) and get mine for over 1/3 off at backcountry.com outlet. I did the same for my Montbell windshirt, except that the only color that was available on closeout looks like wine vomit (what we go through to save money!). Do remember that Montbell's sizes run small! You may find that you need a size larger than you normally wear, especially if you're a borderline size.
Your base weight is already sufficiently low that you don't need to be in a hurry. Do more research (compare with others' gear lists; there are lots of them on this site) and identify other items where the weight savings can be significant. The list guidelines for the backpacking course at http://www.backpackinglight.com/cgi-bin/backpackinglight/wilderness_trekking_school_gear_list.html is an interesting source. Check out Mark Verber's website, which I recommend to everyone. Watch for sales and % off coupons (keep an eye on the "Gear Deals" forum section). Before you spend, divide the price of the new item by ounces saved. You may decide the weight savings are not worth the money!
Remember that skin-out weight is just as important as base weight. My most significant weight savings in the past year have been in switching from boots to trail runners (which lightened both my footwear weight and sock weight) and from heavy aluminum to carbon fiber trekking poles. Neither change affected my pack weight, but both have had a very positive effect on my hiking comfort!
Keep track of things you don't use, with an eye to possible elimination. Of course some things you shouldn't eliminate--don't leave behind the rain jacket just because it was sunny and warm during your last trip.
Good luck in your weight reduction quest, but don't go overboard. You will undoubtedly find, as I have, that some things work for you and some don't. Don't try to accomplish too much at once. There's no big hurry.
Consider publishing your gear list. The folks here will go over it with a fine-tooth comb and may really surprise you with suggestions for eliminations. (Mike C will of course insist you leave the TP behind.) Click on "Change my profile" and upload your list (be sure weights for each item are included), then make a post in the gear list category asking for comments. You'll get them!