Advice for 7 Week Old Runt

***Disclaimer*** This was not intended to be one large paragraph.. the return isn't working for me on this browser, nor any of the text icons above. Thanks!*** Hi, we rescued a 4-5 week old pit bull that was the runt of the litter. We were told she was 6 weeks and weaned from her mother, however; our vet is certain she was 4-5 weeks at the time. She weighed 3.8 lbs. Now, at roughly 7-8 weeks, she is not showing any signs of improvement in behavior. She has gained some weight though. We do ask the advice of our vet, and we have read articles online, however; it would be great to hear from those that have experience with this situation and how things turned out. The puppy, Minnie, barely eats, she has no interest in drinking water (we feed it through an eye-dropper and wet food), she seems to mope around and not engage in too much activity, she's been treated for a UTI and in her last few days of antibiotics so any bacterial issue should have been treated as well, and she angrily bites hard enough to draw blood. I say "angrily" because we have witnessed her playful biting but this is different. She curls her lips and snarls before snapping at hands, legs, face etc. Her playful bites are too hard also, but we've been "yelping" and acting like it hurts so that she learns. She also has no real routine to eliminate. Sometimes she poops and pees after eating... sometimes she doesn't. Sometimes we take her out, she pees, then put her back in her crate where she pees 2 min later. She will poop zero times at night, or 3-4 times. And she lays in it. We've tried all the tricks hoping she would see her crate as her den to no avail. For example, we feed her in her crate, we've made it smaller, we take her out at set times etc. We have not seen a difference yet, any additional info or advice?

Advice for 7 Week Old Runt