I have managed to successfully downsize my handbags. A lot. In the beginning it was difficult to limit what I carried. I have always packed everything I thought I *may* need into my bag each day.
This last weekend I used my Rebecca Minkoff Chevron Quilted Small Love Bag (bought at 70% discount because the lock was slightly discoloured) and Anya Hindmarch bag strap (bought second hand). The combination of the bag strap and the pink Coach tassel (a charity shop find), plus yello Metallica tour key ring was kind of cartoony. I really enjoyed carrying it. This strap is incredibly comfortable and can be adjusted to four different lengths via the poppers shown below.
Over time I have learned to carry 2 aspirin instead of 24, 6 pieces of gum instead of a box of 36, one pack of tissues instead of three, and so on. If I need to carry paper for work I carry one original and make photocopies on site instead of printing everything at home and carrying it around all day. I also email documents to my students and ask them to bring their laptops to class rather than taking all my resources with me on paper.
Over weekends I just carry my planner, phone, 10-pack of tissues, 3 hand wipe sachets, and 3 glasses wipe sachets.
This Anya Hindmarch bag strap has been one of my best purchases. It is so pretty and can bring a new pop to any bag. It is adjustable via poppers, and is really really comfortable to wear. I love the gold hardware because I mostly use handbags with gold hardware.