If you carry on you will DAMAGE and loose the Bootcamp partition !
You have MORE than three partitions - there are two vary small hidden partitions - EFI and a Boot Rom for Windows.
If you use Disk Utility as sure as eggs are eggs your Bootcamp will break.
What you need to do is back up your Windows Partition to an external HDD.
Launch Bootcamp Assistant from your Utilities folder under Osx.
Recreate a single (visible) partition structure
Resize Bootcamp and reinstall windows.
Long winded but ONLY SAFE way.