Snelly, had exactly the same issue last this year with new irons, trust me you will not get used to being a club shorter! I was doing the same as you, sometimes a club more than my mates and still being short! I went back and changed them in 2 weeks!
It's nothing to do with air temp or hit it harder, i'm also a smoother rhythm swinger and you shouldn't have to change your long established swing to suit new clubs.
What's the difference in weight between your old and new shafts?