Best birthday gifts, must be in my budget though

If you make her a birthday cake yourself, that would be very sweet and shows that you care about her.
If she is into fashion and clothes, why don't you get her a magazine subscription to Vogue? I would love that. Maybe buy the current issue and tell her she will be getting more in the mail. I do not think that is too expensive. Good Luck and have fun with it.

try the most seductive scented (to you) perfume wrapped up in a designer scarf, if that's what she would wear.

ROSE and TAKE HER 2 DINNER

Get her what she really wears.
I would love that if my boyfriend did that to me.

You're doing the right thing by putting thought into her birthday present, that's for sure. If I were you, I'd go to a department store and ask the workers their what the most popular shirts are, pick one and then ask what jewelry goes with it. Earrings, necklaces, bracelets or a ring (not a diamond so soon though!) are always a good idea for a girlfriend's birthday gift.

The most romantic gift you can give is something that YOU KNOW SHE WANTS. Not what you THINK she wants, or what you want her to have. If you put some thought into it, recall past conversations and see what you know she would like. If it's in your budget, go for it. If it's too high, try to find something along the same lines, but not a knock-off.

My wife loves purses, so when we were dating, I found a wholesale lot of 10 purses on eBay for really cheap, and I gave them all to her at once. She was surprised and very pleased.