I know that if she's the right one, I can be in a relationship with her, but I haven't asked her out because it's just so hard for me to get started. The fact that you have been in relationships in the past is a very good sign. It seems that if you could only skip over the first four dates you would be just fine. Perhaps a different approach to dating would enable you to acquire a greater sense of familiarity and comfort at an earlier stage. Since making conversation with a woman to whom you are attracted does not come easily to you, try to plan dates that focus less on talking.
Shared experiences can become catalysts for more natural conversation.
Go ice skating or take a bike ride, invite her to a new exhibit at the Museum of Fine Arts, a concert, or even a movie. It's perfectly okay to explain to the person you are dating that you prefer this way of getting to know each other over sitting across a dinner table. She may be relieved. You will get to know each other through the shared activities and the conversations they evoke. No matter how activity oriented your dates are, there will still be uncomfortable moments, when you don't know what to say.