Biting and growling

 What she said!

When you are training, you use small bites of something very tasty - a high value treat.  You can use a hot dog (which is cut into at least 60 pieces -- SMALL bites).  You can use string cheese or cheddar, and I also use boiled boneless skinless chicken breast.

When you start, you have the empty dish as the obstacle - no food in it.  Do that several times in a row, then stop.  Do this twice a day, three times if you can.  Then put maybe a toy in the dish.  Work your way up to food and even then start with something she doesn't really like (if there is such a thing lol). 

Hold her on your left, with the dish on your right, and walk past the obstacle. Do not permit her to cross in front or behind you.  If she does, don't keep moving forward.  Stop, back up, let her settle, then start again.  So she gets the idea she only gets the reward - the treat - if she makes it across the room.

I don't think you need a behaviorist (which is one on one and expensive) as much as group classes.  Less money, this may be an option for you.

Moving away reinforces her behavior.  She's successfully moved you out of her space and claimed the food.  Dogs know how to claim space and food and they expect humans to understand the signals they send warning us that they're going to bite unless we back off.  She's learned that biting works, so you'll have to work hard to change her behavior. If she's not crate trained, do that first. 

Teach her "leave it".  Here's a good video.  http://www.youtube.com/watch?v=zNAOe1djDyc  This trainer has a lot of helpful videos on her youtube channel.  Until you have trained a solid gold "leave it" command, manage the environment.  Crate her during food preparation or eating.  The more you can reduce the chance of her being aggressive around food, the faster you can change her feelings about you being close to what she considers her food. 

Teach her to get in her crate when the doorbell rings.  This training goes quick but you'll need a helper.  That person rings the bell but doesn't come in.  You're near her crate, standing calm and still, with yummy treats.  If she runs to the door, ignore her and wait it out, near the crate.  If she comes back to you give her a treat and praise her wildly. Repeat until she prefers staying at your side and ultimately is getting in her crate, when the doorbell rings.  Your goal is to have her run into her crate when the doorbell rings so you can shut the crate door and greet your guests.

The following dog trainers/behaviorists have great websites with  videos and articles.  You'll find help with your dog's problems if you spend some time exploring their sites. Reading about how to change your dog's emotional response to certain situations should be your top priority if you can't afford a consultation with a professional. 

Dr. Sophia Yin

Jean Donaldson

Karen Pryor  Don't Shoot the Dog is the book I always recommend first.

Patricia McConnell

There are others but these will get you headed in the right direction.  The key to changing a dog's behavior is educating yourself on how dogs learn best.  There's no magic method guaranteed to cure a dog of any problem in X number of days.  It's discouraging at times but if you're motivated you can do a lot to improve her behavior. 

Good luck.

 Two things you can do right away that won't cost you a dime:

1. The dog no longer gets access to human food or an area where food is being prepared or eaten.  I recommend using baby gates (I have used ones people have given me or I get cheap at a second hand shop) to block her from the room or use a crate.  If she can't be nice then then she has no right to be free in that area until she can control herself.

2.  Google "Nothing In Life Is Free" and start using this protocol when you interact with your dog.

 Agree with everything. She no longer gets free access to high value places (doors, kitchen, ect) Baby gates are a great investment and not to expensive. You can usually find them in a second hand store.

Now, Do not back up when she bites or growls. Body block her from what she wants, and shuffle her slowly away from the object(wear shoes or slippers). Don't use your hands. Keep a long line on her at all times when she's with you. 

The books Jackie suggested are GREAT reads.  I would also look into group classes. I really feel that this is a dog that would benefit from being in a group instead of one on one. But when researching trainers, find a positive trainer who has experience with your issue.

Good luck.