You don't want to breed two poorly bred dogs together. The pups will be of lesser quality than either or both parents. If you had a quality dog you would not have to go looking for a female. & not just any female will do. You need to be able to recognize the faults in your dog & the faults in the female & not breed them if they have the same faults. They both should come real close to the standards.
If you had a quality male the owners of quality females would be ringing your phone & knocking down your door. A good quality male & a good quality female & not just any female would do. Selective breeding is what makes or breaks a dog.
Just because they are both registered doesn't mean much unless the dogs at least comes close to the standards. Things like ear set, eye set, angulation in both the shoulders & the hips, the stop has to be just so so, the chest just so so, the line of the back, gaiting faults, the list just goes & goes on & on.
I have a GSD that would make for a good little mama but she is a poor quality dog & was spayed as soon as I got her. She is too big for a female, her angles are all wrong, no sickle hocks, she is boxy instead of long. one ear does not stand & on & on & on.
Study the standards for the Doberman. They are my favorite breed & I would love to have a high quality german bred red female Doberman but I will never in my life time be able to afford one. $2,000.00 to $5,000.00 is a bit stiff. She would be of breed able quality but I would not breed her. I would be afraid of what would happen to her pups. & I am too old now to go into showing her & going that route.
LOL your dog does not NEED to Do his THING. They find no pleasure it, they are pulled & pushed by instinct.
Think before you act. Study the Standards Learn as much as you can about the breed, where it came from, the anatomy, reproduction cycle, standards. Personally I would have him neutered.