parents cross boundaries too much

I'm in my mid-30s and although I'm in a 3-year serious relationship I'm very happy with, my parents simply cannot stop asking me when I'm getting married. They have always considered our family "close-knit," assuming that their children have no reason to be uncomfortable talking to them about anything. The truth is, I don't like to talk to them about my personal life. However, my father in particular feels that if I cannot give him answers to his questions about my relationship-- when are you getting married? Has he talked about it? Have you brought up marriage? Why not? You're not getting younger, do you realize that?--then there is something terribly WRONG. I've tried to tell him nicely that it's none of his business, but he just shrugs off my words and says, "you're my daughter therefore you are my business." It makes me feel like I'm his property, not his daughter. He calls me once a week and because we live in the same city, he asks me to meet for lunch, but those lunches end up turning into grilling sessions. I no longer want to meet up with him. The last time we spoke he told me I'm going to end up becoming an old maid. What a wonderful thing to hear from one's father, no? Honestly, it all just makes me want to pull away from him, and my mother doesn't help much either. She's all up in my business too. Most of them time whenever I talk with them on the phone both of them get on the call and start yelling at me about my age and that I should dump my boyfriend.

I don't know what to do anymore. I know some might say, they're your parents, they're getting older, that's just how they are and they love you, but quite frankly, I'm sick of it and I'm sick of their lack of respect for personal boundaries.