How to Come Out to Someone Who Just Doesn't Understand?

Prepare for long blocks of text, I have a hard time keeping things short but I tried, I'm sorry ;-;

I'm 14 years old, mostly lesbian, and out to probably about half the people I know, but the only people in my family that know are my mom, step dad, and my two brothers that are both about a year younger than me. I'm comfortable telling most people, and the only reason many people don't know is because I keep it on a need-to-know basis. This, though, isn't about those people. This is about coming out to my dad.

So, I've tried coming out to him twice before. The first time was by accident, I was sitting in the living room with my dad and little sister, just watching tv while I was texting my friend (current gf) via skype. Suddenly, she said "hey, I have something to confess to you" and I knew that she was about to tell me she liked me, because she'd discussed it with my best friend beforehand, who had then given me a heads up about it. So I got really excited and my sister started to bother me, and I turned to her and said "leave me alone, I can't talk right now I'm about to have a girlfriend!" and my dad heard. I did that by accident, but wasn't too worried, because I figured now was as good a time as any to tell him. He took it as a joke though, didn't think I was serious...

(note: my gf's name is *not* actually Rachel, but I am using it in place of her name as a security measure instead)
I'd been dropping hints since then, and tried again a few nights ago when I said I was planning to go to a movie with someone, of course he asked who and I said Rachel, specifying that she was my girlfriend. I had mentioned several times before that she was my girlfriend, most of the time he thought I was just joking. So then he said "Oh, you haven't told me much about her. She's your friend that lives by your mom, right?"

Later, I asked him what his views on the LGBT community and lifestyle were, and he went into this long explanation about how he thought they were "okay" and how he thought "it was disgusting, but it didn't affect him" and he said he wouldn't tell anyone how to live their life, so it didn't matter to him. He then went on to add that since he didn't know anyone who was like that, he didn't know a lot about them. Overall he didn't have too bad a reaction, but what he said made it clear that even after I had stated several times that she and I were dating, he still thought there was no way that I wasn't into guys.

When he asked me what I wanted for Christmas, he also added that I couldn't have a teenage boy no matter how much I begged. He thinks jokes like that are funny and says things like that all the time, which make me really uncomfortable, and I do correct him every time. I just feel like I couldn't be making it clearer that I am not straight, but I can't tell if he just isn't understanding, isn't listening, or is in denial. How do I come out to him and make him understand when I thought I had been doing it so many times already??

 

Aww, thank you ^^

And I guess that makes sense, I just thought I was making it clear enough, but since he has no experience with the community it would make sense that he didn't realize that I was being literal. I'll keep that in mind, and possibly try that out tomorrow if I can catch him at the right moment.