You are NOT nuts... BUT I have had mine since release as well and now when I go to look for old photos on my 5S I am like... wow this little baby screen is so tiny... how could I ever have enjoyed looking at web pages / Facebook / iMessage on that tiny screen?
Honestly viewing web pages is so incredible now.
I myself was also thinking about switching to the 6, but in all honesty, after a couple more weeks I am 100% sure the 6+ will seem totally normal and not too large.