I accidentally said "I love you" too soon to my girlfriend and I think I may have ruined it?

Little background:

I am twenty three, and I met my current girlfriend online from a dating website because neither of us have time to go out and meet people with our busy work schedules. We talked for a couple months, went on some dates and really hit it off. She is pretty, sweet, nerdy, and is a very genuine person. She has met my mom and I have met her parents and friends. They are all happy for us. I asked her to be my girlfriend and she said yes.

Now we have been dating for about two weeks officially, and last night we were cuddling watching a movie. I accidentally let an "I love you" slip. Her reaction was "WHAT?!" and seemed a little freaked out by it.

I didn't know what to say so I just let it pass. About 10 minutes later she pulled away, and started acting kinda weird. She wouldn't go near me, and she wouldn't even hug me when I left. Now, she is not answering any of my texts, not responding to anything.

I do not know what to do. I do care about her a lot, and I do not want to mess this up, as this is the first time that I am genuinely happy in a long time. What should I do?