The game wasn't especially clear on how many doctors to kill.

I stood there for 5 minutes in that room trying to do anything else but killing...

That's the spirit, burn the idiots everyone who has completed the game and paid some attention to the audio files in the final chapter knows why they are idiots.

LOL. I've lost it with "juno everdeen and old Nathan drake."
About the doctors, I played the game 9 times and I always do the same thing, which is to kill the first doctor and spare the other two. I couldn't bring myself to do something else no matter what.

I was always under the impression that the other doctors would attempt to stab you if you grabbed Ellie without killing them all 1st

I guess it's due to how the hospital level was handed in term of story and gameplay. Throughout the game, you can sneak around the areas using stealth and minimum killing. But in the hospital level, the game is forcing you to do what was basically a cleansing of the fireflies as way to show how Joel will do anything for Ellie, which means no one will be alive because "you'll come after her" in his own words to Marlene. By the time I reached the operation room and killed the 1st doctors, I felt something was wrong but it didn't hit me until the nurse said "you're a fu*king animal" and later begging for her life then I realized the truth which I found it hard to digest no matter how I tried. Joel isn't better than the other "bad" guys in the game. He is survivor, and will do anything to be that way. 

I'm mainly commenting to watch this later, have no sound at work however, I didn't even realise killing the doctors was an option, the cutscene killed the first one, then I picked up girly and ran. But by then I was far from in control of this character anymore. Just like in Spec Ops The Line, I could not longer stand the character I was playing, sure I did the killing and shooting but only to guild this character to their destination. I made Walker shoot himself in the end, if this was an option for Joel, I'd do the same.

Hence why I put "bad" in a quotation marks. He isn't like the cannibals, but more like the hunters. But thats not the point, what I'm trying to mean is  by the time you killed everyone in the hospital and that nurse calling you by an animal and begging for her life was the last straw to realize if Joel's decision was right or wrong. The logical part of me says it was wrong all of that killing. But the emotional part of me was with it because Joel deserve some happiness and a second chance to be a father again. This why I love the game, it makes you think a lot about many aspects instead of choosing one "truth." I tried my best to explain my point, but English isn't my first language to begin with. 

always wondered what happens if you didnt hi five ellie

LOL thanks for the compliment. My English fails me whenever I try to explain what's going in my head. I guess that's what you get for learning English at a later grade. When I was at school, English was taught from the 7th grade and above, but now it's from 1st grade. But I'm trying my best to work on it hehehe XD