First off I want to say great job, you had some balls and you escalated like a champ. You kept persisting a couple times when she gave you some resistance which was awesome.
Here is the thing, I think she likes you and is okay with you doing this because. First off she didn't give any resistance making out and was letting you run your hands all over her body then and there. If she was not wanting you at all she would have been giving you non offensive excuses to try and get out of it right then and there. She probably suggested to get something to eat to bring it back to a situation where it was more comfortable for her. But THEN after you ate she was totally cool coming back to your place and made no bullshit excuses or tried to get out of it (saying she was tired, had class the next morning). She then came back to your place and sat right on your fucking bed. Girls who are really creeped out and don't want guys coming on to them.... do not go and sit on their bed. She stopped you only when you tried to transition to sex which pinpoints to me that THAT is what she is uncomfortable right now. I think that these are the things that could be standing in the way here.
YOU HAVE TO REMOVE ANY HANGUPS SHE HAS
-make sure that you deep dived well. She should feel that you find her sexy and would love to pin her down and fuck her... but you just as strongly value her for the intriguing and unique individual that she its. Make her feel sexy, and unique and special.
-Make sure you communicated with her that you respect sexually liberated women. Where society views a “slut” you see a confident girl who is aware of the fact that we are only sexy and young for so long. This way she wont be afraid of looking like a slut in her eyes if she gives it up soon.
This is what I think the big one is tho...
YOU HAVE TO GET HER TURNED ON AND MORE EXCITED
I think that the way you probably went about this was very mechanical like a process “okay... now here I gotta start touching her here” and you were so focused about just getting any girl in bed and getting a lay that you were not focused on giving her the emotional display that she needed to get horny. In fact I know this is the case because you said that you think she isn't that attractive. What makes women horny is when a guy (a guy that they like) is so fucking turned on by their sexy body that he is literally loosing control of himself and cant stop himself from pinning her down and ravaging her with all his primal desire.
Go on the internet and find a video of just the audio of girls who are having sex moaning, you will literally be able to feel your body react to it. Now imagine girls just saying “oh, oh, ughhh, oh” in complete bored, monotone voice. Wouldn't have the same effects now would it. This is our limbic system reacting to others emotions. It has little to do with what you are doing and everything to do with HOW you are doing it. Its all about proximity, facial expression, breathing, tone of voice.
I want you to imagine that you have the absolute sexiest girl that you've ever seen in porn and shes sprawled out on YOUR bed naked, hornier then she has ever been in her life, and she gives you the amazing opportunity to do whatever you want to her incredible body... You are holding her by the hips, fucking her sweaty, perfect body as hard as you possibly can, loosing control of yourself, its the most amazing thing you have ever felt and experienced, you are just about to cum. How would you be breathing? How would you be moving and touching her? What tone of voice would you be using with her (if you could even form a sentence)?
THIS is how I want you to treat every girl that you get home alone with you after you start to heavily make out... regardless of how she looks or how attractive you find her. The mind is the most powerful sexual organ. I can tell you that THIS will get a girl more wet and more horny then any technique or type of stimulation or anything else EVER WILL.
-People are a lot more socially sensitive and intuitive then most people think they are. I think that this girl can pick up on the fact that you are just trying to get an easy lay with her because she is below your standards and its easier on you. She enjoys having a guy touch her... but she doesn't want to give in in a situation like this as it would hurt her self confidence and feelings.
lastly when she asks you “what are you doing” just be completely unashamed of your raw sexual desire and do something like this
Her: “What are you doing?”
(you are EXTREMELY horny and breathing heavy with everything you say)
You: “You tell me.... what am I doing to you too you right now sweetie”
Her: “You're reaching up my shirt... grabbing my boobs”
You: (super horny whisper) “Ohhhh..... thats right baby”
You: “I bet that feels so fucking fucking good for you right now sweetie, doesn't it?”
Her: (some shit about how shes not comfortable with this, even if she is horny)
You: (hornier and breathing harder then ever now) “Katie.. you're so fucking sexy!.... I can't control myself around you.”
Then you attack her like the horny savage you are and dominate her, giving her the most emotionally intense sex of her life.