Is it normal to be over protective of friends and bfs?

Control freak alert.

I am a female, and I am protective of my friends. Needless to say if someone started a fight with them, even though I'm small I would be the one ending it(:

Do you bark too? :P

You need to say more about yourself, this is just insufficient info.

There is a difference between over-protective and protective. For example, if you are willing to stand up for them against somebody that was or is being mean to them, then that's an example of being protective. But if you are willing to beat somebody up just for being rude to them (i.e. stepping on the back of their shoe or not saying thank you) then that is being a bit too over-protective. You should try drawing a line between how far you're really willing to go to protect these people from harmless situations.

Being overprotective is a sign of your love for them.

Aah, I know a girl from some forums who was like you defending her friends and standing up for them (both verbally and physically). Her story was similar to yours, including that 'friends' part.
One of her female friends even (so she said) started to flirt with her.

But when she had an accident (and it was their female friends' fault) where she got pushed through the shopwindow glass and got her arms all cut (and it was for an operation) she saw her friends for what they really were (not).

In the end she distanced herself from those friends almost completely when she got a boyfriend and serious relationship. An then one was even trying to flirt with her boyfriend so she broke contact with them completely.

So your girl friendships seems like a pit of snakes to us guys. Lol xD

I don't know how old are you (she was like 19 then) but don't put yourself too much into such friendships. You'll likely only be used without words of thanks.