Shepherd with Shepherd, Shepard with Doberman?

Female dogs breed only when in heat and due to instinct, to reproduce - NOT for sexual gratification  They do not DO IT for enjoyment & from the complaints and sounds DO NOT (often) enjoy it.  Their instinct will DRIVE THEM, and they will breed with any number of males - if allowed to get out during a heat cycle.  Dogs do not differentiate "BREEDS", so who is not as important as whether they make an impressive display, fight off others to get to her, or are simply very assertive or persistent, etc.  

It can be a deadly experience if a much larger dog, manages to breed with a smaller female.  She may not survive the size of the puppies growing in her uterus, or may not be able to birth the larger heads - though her pelvic canal, certainly NOT without a C-section by a vet (which can cost $2,500.00).

Own a normal dog, the animals you noted are all specifically for military and police use.

A common citizen should never own a shepherd, they bark far too much and can easily bite someone.

I have a neighbor that owns a german (nazi) shepherd, I have called the police a myriad of times because of the barking; huge fines were administered.

Additionally, why do you feel so frightened?

You don't need a big dog to feel safe, don't you have any belief in yourself?

a male dog will try and mate with any dog in heat

Dogs do not care about what breed the other dog is.  They are driven purely by instinct to mate when a female is in heat.

 Baaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaah

a male dog will mate with any available female in heat.

A female in standing heat will typically allow any male to mate with her.

They make no discrimination based on breed.

They dont "enjoy" mating.  They only do it because instincts urge them to mate

 A Male dog will mate by instinct with any female dog that is in heat, regardless of breed.

A female will accept any breed when she is ready to mate.

No dog likes to breed with a Shepard, because Shepard is not a real breed.

Yes, my dog, in particular, will ONLY mate with Dobermans.  She has a dislike for other breeds, probably was bullied in the past.

A male dog don't give a damn what she is, if she is in heat he will fight to have the right.  Can't say dogs enjoy it, it is part of natural & normal Canine Behavior.  It is an instinct & part of the canine reproduction.  Humans are the only animals that copulate for enjoyment.