Are you quiet around your friends and family or just people you don't know?
If you're always quite quiet then that's just you.
If you're talkative around your friends and family but quiet around new people then it's just a confidence problem.
If you're quiet around your friends and family but talkative when you first meet people it's another sign of a confidence problem because you're trying to avoid awkward silences.
Needless to say if you're always talkative then that's just you.
When I'm with my people who I know well I can be quiet but when I can go on a bit when I'm talking with someone who has similar interests. On the whole I'm more introvert than extrovert.
I'm not mega confident: when I'm nervous I can be quiet or talkative depending on the situation.
If you're quiet then don't worry about it, women are generally more verbose than men and are generally more happy with a man that listens more than he talks.
Don't think about how much you talk, if the two of you can't hold a conversation then it's not meant to be.
Going from what you're saying you don't sound like you're very confident. My advice is join clubs, go out, meet people. I know this is rich coming from me who spends most of his time on forums like this rather than socialising.
Have you ever been bullied before?
I have.
Don't worry too much about what people think, especially bullies. The whole thing about standing up to verbal bullies is rubbish. If people insult you then it's normally best to agree with them in a sarcastic manner rather than being defensive or aggressive.
You're an idiot!
So?
You're mum's fat!
I know!
Your retarded!
You're point being?
Shut up idiot!
Don't have to if I don't want to.
You get the general idea: they'll soon get bored of trying to bully you and move on to someone else.
Most bullying starts of a verbally but if you think someone is going to hit you don't look scared and don't be the one to throw the first punch. Stand firm, if they hit you try to block or deflect it, only retaliate if you think they're going to hit you again. Get out of the situation if you can. If someone does hit you report it to the police, teacher, your manager etc. don't let them get away with it or they'll do it again.
I know this is all easier said than done and I can assure you most of your worries are needless.
I wouldn't recommend online assertiveness, dating training courses that you have to pay for - all they want is your money.