Hello Caterpillar girl!
Your 10K and HM times sound practically the same as mine - so I'm certain you can improve on your marathon time!
My HM PB is from last October (1:33:08). I ran FLM this year and followed the sub 3:30 schedule. Finished in 3:15:49 (I was a bit surprised I have to admit). I did modify the schedule though due to a knee injury in January as I just couldn't do all the runs....generally I was swimming Monday and Friday, and running the rest. My intervals and tempo runs were never as fast as the schedule suggested - particularly as the long runs got longer, my speed drops off. i also did more long runs than suggested....I basically built up to 20 as soon as I could and stuck there. I managed 7 x 20-22 runs over the last ten weeks which i think really helped.
Anyway - don't know if this helps at all. I like the RW schedules as they give a bit of variety, and the weekday runs generally aren't too long (compared to P&D) for example so i can fit it around my work.
How old are you by the way? I'm 35 and worrying that age may be starting to count against me soon!
What are your plans for your next marathon? London on GFA next year??