Looking at your photos, the first photo it looks to me like your garboard is falling where it should, roughly up to bulkhead F. Your second photo looks to me like you have the issue I also had when I first starting clamping down the plank, I started in the middle and worked my way back and when I got to the stem I ended up with a wedge shape between it, and strake #2. As dumb as this may sound, starting at the stern post and clamping that little bit down so it lies against the rabbit and strake #2 first, and then working forward made all the difference in the world.
Looks like you are using yellow glue, you might want to try CA instead. I'm using Loctite Liquid Super Glue (the bottle is kind of shaped like a nail polish bottle). A drop or 2 on just the bulkheads, 2 or 3 at a time works great. You will only need a few extra drops where the planks lay flat on the rabbit near the stem. I only need to hold the plank for 5-10 seconds and it's set then I move on to the next couple.
I agree, we shouldn't need to buy sheet wood for a complete kit. I did it out of laziness and expediency. I just ripped out the front 2 strakes (not the garboard) and I'm going to try soaking and edge bending the planks just to see if I it can be done. To be honest, spiling planks from sheet takes a lot more time to do than it should and edge bending these would save time in the long run. Good luck, I'm watching your build and it's been helpful seeing someone else struggle along with the same project.