It sounds to me like she is stressed. How long have you had her? Reptiles need time to adjust to new surrounds just like any other animal would.

Feeding in the tank does not cause tank aggression. I have around 30 snakes and I feed them ALL in their cages. Feeding in the cage is less stressful on ball pythons and tends to be easier when you have more reptiles. I have a few that more than likely wouldn't eat for me if I tried to feed them outside of their tubs.

I've also been bit before without being hissed at. You won't always get hissed at and they won't always ball up. A tense snake is a stressed and defensive snake. She is hoping that striking at you will get you to leave her alone. With my snakes I see that if their whole body is tense they are more than likely going to strike at me and they are stressed, when feeding they don't tense up like that.

How is your tank setup? Is it open on all 4 sides? Putting black contact paper on three of the four sides could help her relax a little more. Another thing you can try to do is take a paper towel tub and gently tap her on the head to snap her out of strike mode before you pick her up. I did this with a few of mine when I first got them and now I can just reach in and pick them up. I hope that helps.