I will guess she will be 20 to 25 inches at maturity and has practically all that height now. The white with black spots could b a little of the Border Collie or Dalmatian showing.
What puppies need is a complete and balanced diet, and not too rich and no more than enough to keep their ribs from showing. The only practical way to make sure she is getting the diet she needs would be to feed her an adult chow, and little else. Otherwise, it is very difficult to make sure she gets everything she needs, but not too much. Too much of too rich of a diet leads to excessive weight gain and joint problems later in life. Her ribs are the only reliable guide to how much to feed. Most dogs will thrive on most commercial dog chows.
Since your dog is at past 4 - 5 months old, start with a good 6' leather
leash and a sturdy slip collar, the metal chain ones with the rings on each
end. You want the shortest one that will go on and off easily. If you walk
with the dog on the left, pull the chain through one loop forming a "P".
Facing it, slip it over its head. The free end should come over the neck to the leash, and the other end should drop slack when there is no pull on the leash. Before 4 months use a conventional flat collar to protect the tender young neck.
Easier dogs will give up their pulling with a few good snaps of the leash
combined with a stern "Bad dog!". You can work up to forceful corrections
with the leash doubled up in both hands and your whole body behind it. But
you don't want to use any more force than you need. One gentle technique I
like is to just stop when he pulls. He wants to go. If you move forward when
the leash is slack, and stop when he pulls, he should quickly figure out the
only way to get to go, is not to pull. This is about teaching him not to
pull, not getting somewhere. The man that taught it to me said "If in a half
hour you haven't made it out to the front walk, fine, you have taught him a
lesson.
Still, you may want to switch to a head collar. The leading brands are Promise, Haltie, and Gentle Leader. They have a strap going around the dogs nose looking something like a muzzle. They work by pulling the dogs head around. No other way gives you such great control with so little force. Never use the same snap of the leash as with the slip collar. The prong collar is now a dangerous relic of value only for its macho looks. Do not consider using one without hands on instruction from somebody with plenty of experience with them.