A German Pinscher would be perfect for you! (average size of male German Pinscher is 30#)
They are not like Miniature Pinschers. They are like little Dobermans and look like Manchester Terriers.
The German Pinscher is the foundation dog upon which Louis Dobermann based his breed.
[and yes, I’d love to have one but they’re just now returning from near-oblivion and probably cost a fortune!]
:D
In fact, Dobe breeders have been considering reintroducing GP lines back into Dobe lines to try and negate some of the current genetic problems.
It will take a while to make a significant impact but sounds extremely promising.