My dog chases cars and bikes and doesn’t come when called...?

I have an 11 month old female shepherd named Tasha. I have never owned a dog before and I've been very surprised at how much work she has been the entire time. At this point Tasha is not very trained and is in her adolescent stage. I've gotten very frustrated with her and I'm looking for your advise because I'm at my wits end now.

First let me start by saying that I've not taken as much time with her as I'd imagine I should have. I am a mother of two girls and have only so much time to spend working the dog. Her behavior is as follows: She sits, stays and lays down briefly for treats or a toy. Beyond that she never comes when you call her, if she gets out of the yard she chases cars and bikes and whatever else is moving quickly, she barks aggressively at strangers and all other animals. She is defiant when I tell her to go outside, she runs around the furniture until I pick up a big pillow and swing it at her. She is constantly pestering us to play fetch (day or night) and never stops. Get the picture?

At this point I've tried dog training class but that is too expensive to continue on my budget. I've tried a Haltie because my hands were hurting from trying to walk her on the standard choke chain (she is always pulling and needs to be jerked). The last few times she bit the leash and growled at me and would not stop jumping and biting at it. She is very wild when she gets out in public. In addition, she never comes when I need/demand her to! Nothing has worked so far...

I am looking for your advise because sometimes think I have a stupid dog. Everyone else's animal seems to not have the same problems as mine. We sometimes laugh and call her the "happy" dog. Life is too good for her. She is wonderful with me, my husband and daughters. She is never aggressive at them and I trust her with my precious children. This is why I need to know if I am working with a lost cause or if she will mature in combination with training and become the pet I dreamed of.

Sincerely,
Tamara