Hi heartsmart,
I know how you feel - I've dealt with varying degrees of shyness since I was very young, and I'd like to offer you something that may be of assistance. It's quite simple and, if used correctly, can be a powerful and valuable tool: Body Language.
If you observe yourself for just a little while, you'll notice that your body language and state of mind tend to be in harmony with each other, by which I mean when you're in a certain state of mind, you're likely to find your body reflecting that. For example, if you were feeling shy, your body language would likely reflect that in some way, such as your head hanging low and your hands resting in your pockets as you walk around.
But, I learned that this process can work both ways - It is absolutely possible to change your state of mind by simply altering your body language in ways that bring about the desired mental state. So, if you want to feel more confident within yourself, try making a conscious effort while going about your day to hold your head up high, keep a good, strong posture, and stay grounded. If you keep this practice up it's very likely you'll notice a higher level of confidence within yourself before long. It's a sort of "fake it 'til you make it" kind of thing.
There are many resources available online and in books about Body Language - I recommend checking out your local library
Best wishes.