Help on modifying a recipe

I recently bought a bread machine and after success with several loaves following directions carefully, I ventured out to modify a recipe.  I had made a loaf of "buttermilk rye bread";  I like a good rye bread but this bread did not really work for me. I liked the texture very much but the very faint rye taste did not seem to me to work.

Having read that rye does contain some gluten, but not very much, I modified the recipe by substituting (for the cup of rye flour) a cup of equal proportions of hazelnut flour with whole wheat flour.  And I omitted the caraway seeds.  The resulting bread tastes great, however the texture is much different than the original recipe and the top of the loaf collapsed; the overall result is satisfactory but not what I expected.  Apparently the new recipe causes the bread to rise more.  Three possible corrections occur to me and perhaps someone can comment on this: 

1. I need to use less yeast.
2. I need to use less sugar.
3. I need to use some different mix of hazelnut and whole wheat flour.  

Then again, maybe the problem is with the caraway seeds or something else entirely.  I'm new to this bread making activity and could use some help understanding what happened.