I'd feel safe in venturing to guess that your sudden floundering with stories coinciding with Heisig's withdrawal from holding your hand isn't exactly a coincidence.
There's no special secret to continuing from here. Unfortunately, Heisig's withdrawal also coincides with what might be some of the harder kanji.. I'm not sure, but taking a peak into that area, I happen to find some of the kanji I still have issues with, so. At any rate, this is the time you need to grab the bull by the horns and make sure you come up with the stories that really click for you. If you still need a lot of help (God knows I'm too lazy to come up with good stories for every character on my own), that's really what this site is for. I actually go through the book while flipping through the kanji on this site at the same time, reading through other peoples stories before trying to decide on one for myself at all (unless one happens to spring to mind immediately, and even then I take a glance just to see if someone has something better).
So just keep at it. The kanji may be getting a bit more complicated, but otherwise, nothing has really changed. Do the exact same thing you were doing before, just rely more on this site and your own mind instead of Heisig. If you're still having trouble, DO change your method. If you've been going for visual stories, try making rhymes. If you're been relying on word play, try making things visual. Try drawing pictures, or making little songs. Relate kanji keywords to experiences in your childhood (this often works RATHER well for me). You can do it.
I believe this is a phase most all of us go through, but we tough it out and figure a way to make it work. I believe it's also a common quitting point for a lot of people, either on their 'first time around' or permanently. Don't let it be either for you