I've been with my boyfriend 1 year today and I STILL haven't heard those 3 little words yet. And yes, you know what I'm talking about I LOVE YOU. I told him about 4 months ago and his response was 'I have really strong feeling for you'. Since then, I haven't said it anymore. I feel he will say it when he's ready and I don't want him to feel pressured to say it to me. I know when he finally does, it's going to be really special and I know he means it. Everything he does shows it. Like the saying 'Actions speak louder than words'. But I guess I just want that security hearing those words. Plus, we live together now. Next weekend, we're going away to St. Louis Missouri for a 3 weekend get-a-way to celebrate our anniversary and he can't be anymore excited about it. So, my question is, should I say it again, or should I just keep waiting. And, if he keeps me waiting, how long should I put up with it?

This isn't about him keeping you waiting. This is about him wanting to say he loves you and meaning it at the right time.
As for saying it again, you've already put it out there, and if you don't want to pressure him then maybe that's not the best idea, but if you feel that he is ready to say it and needs a little nudge, then go for it.
Have fun on your get-a-way anniversary.:)

I completely understand what you feel.It'd be a problem if you heard that before a date,LOL.(that happened to me). He takes things slow, that might be the right thing. BUt everyone is a little bit different, he might just be like this. It's hard for a man to say "I LOVE U", I think you should give him a little bit time. Wait longer... good things come to those who wait:)
What type of personality does he has, by the way?

NO. When me and my ex fiancé started dating she told me within the first 3 months. I felt very uncomfortable when she said. At first I didn't say it back then I just mumbled it because I didn't want to hurt her feeling. She did get mad when I did this. I just told her I don't feel that way wright now. After about 6-7 months into our relationship I did say it. And when said it I meant it. So no I would not say it again until he says it.