I can't see your photos, but will offer a few thoughts.  When you stitch the two hull panels together the stitches need to be "finger tight" (from the manual).  Finger tight for you might be loose for a builder with tough fingers.  Those stitches need to be snug enough that when you open the hull panels, like butterfly wings, the panels bend up at the bow, similar to what is shown in the manual.  The very tip of the keel line might be slightly open (see picture in manual), but the rest of the keel line from at least Frame three to the bow needs to be together.  If not, fold your hull panels together again, snug up the stitches, and reopen the panels.  If this is really difficult, take apart the hull panels and sand the two touching corners of the keel line so they are slightly rounded, say with a radius of less than 1/16", just enough to take off the sharp corner.  That might help you keep the edges aligned as you fold out the hull panels and still keep the stitches snug.

When you first insert the notch at the bow end of the opened hull panels into the inner stem, you need to get the panels as far into the inner stem as possible when snugging the stitches holding the pieces together (helps to have extra hands to hold things).  Rounding the sharp corner of the bottom of the hull-panel notch is useful, too.  As you proceed, keep an eye on the front of the assembly.  If gaps appear, figure out why and redo.  Small gaps are not a problem at the bow, they'll be filled with epoxy later, and the curves at the bow are not part of the important running surfaces.  But larger gaps, especially at the notch-to-inner-stem joint will mess with the rest of the assembly's alignment.

A looonng stitch over the top of the central web, just behind Frame two, and down through the hull panels behind where Frame two is supposed to land, helps to pull the central frame assembly down into position.  Have someone push down, and forward, slowly on the frame assembly as you tighten that long stitch and others, as well as the screws through the hull panels.  Another stitch or two through the central web's cutouts, through the hull panels and down around the external frame can help to pull things together.  All the holes will be filled later, but you might need more copper wire.

Don't fret over broken stitches.  Replace and snug up slowly and evenly with the others.  If this doesn't help, please reply and I'll try again.  Good luck.

Thnaks for the advice--

I had a much better time yesterday. Was able to get the pieces to fall in place. Now the joints at the bow have pulled apart again. I'm going to try some steel wire, or someting that will hold up to more tension. 

Thank again. I'll report back--