I'm going to say what nobody else will...You NEED to make up your mind about what you want ASAP. Dragging out this desire for something you can't have will only hurt both of you in the end.
I've read the other replies in this thread, and your reasoning behind not taking any action as far as being a flaming bisexual, but not wanting to shock or hurt your boyfriend. And frankly, you have 3 options.
1) You tell your boyfriend you like women more than guys, but still want to be with him. He'll probably ask you what your type is, and if you two have similar tastes, he'll probably try to check out girls alongside you. You've said in an earlier thread that this idea doesn't appeal to you (because you're a jealous territorial girlfriend). Simply tell him you're not comfortable with that, and if he's a good person, he'll stop. But you should be aware that it's either THAT or the second option, which is;
2) Break up with him so you can have sex/date whoever you please without worrying about hurting somebodies feelings. This is the simplest option, but the hardest.
3) You COULD ask your boyfriend is he would mind an open relationship. Meaning, you two can have sex with anyone you want on the sidelines, but relationship stuff would strictly be between you two. "Non-monogamy, is what I believe this is called. If he isn't into it, which most people aren't, you should probably break up with him. The attraction to women won't just go away on it's own.
You really gotta decide already. My goal isn't to be harsh, but to help you. Which option would be best for you?