Kyle , welcome to the world of snakes ...haha
Bloods "hiss" as babies and as adults I am sure other blood owners will confirm this I wouldn't worry about it.
I have never been bitten by any of my bloods but they have hissed alot and had a few attempts striking, its just part of their makeup IMO however I dont agree they are bad biters tbh but some may dissagree I dont know I am speaking from my own experience with them.
I would ranks Retics, Anaconda's above them by a long shot but they are very defensive as babies and can be prone to true and false striking as well as hissing but short periods of handling is best when they are young IMO as in my experience anyway it takes time and patience to get them familiar with handling but they never lose the hissy attitude sometimes.
You should try to remain calm focused and confident around them and keep the handling brief during the training period, I think you will find she becomes more "used" to it as she grows and becomes more confident herself through consistent feeding and shedding.
There is a reason they are not beginner snakes and that to me mainly the ability to read snake behaviour through experience of snake keeping in general.
Whatever you do dont let it dent your confidence , persistence patience and understanding are key factors working with Bloods the way I see it and you will be rewarded if you work on these.
Try and just learn from it, take stock of the situation as it happened and keep it mind an dput it down to just more experience you have witnessed and been part of.
The beauty of these animals like other snakes is learning how they behave and respond and moulding youself to the snakes requirement rather than trying to force the snake to mould to yours.
I am glad to see your gaining valuable experience regardless