How can I limit other (administrator) users access to my profile?

You can't, it's as simple as that.

Try to change your point of view: change every account in common users, then give 'em permission to install softwares, thus holding your super-admin-powers for yourself!

Probably the best solution is for each user to encrypt their files using EFS. While you cannot prevent other admins from listing the contents of each folder, EFS will encrypt the files to where not even an Admin can decrypt them unless it has been provided a copy of the private key or a backup certificate.

Since the Administrator group is built in, you cannot change the permissions for it.