There are plenty of dialogues around here to choose from. Download some and just read them. Get some ideas from other peoples work. When I have a block, I return to older dialogues I've written (and others) and reuse/re work some older lines. A few days come and go and I return to the dialogue to change it once again. Also, you should really add some triggers. To show you what I mean, below is your first few dialogue lines:
wake:"Ass..."
wake:"Wh..what happened?"
vigorous:"I don't know how long I can keep this up.. but I need his cum.."{"style":"Thought"}
vigorous:"Mm, you like this huh?"
vigorous:"That's it, keep me sucking on your cock."
and now we add some triggers...
wake:"[SHOCK][LOOK_UP][BLINK]Ass..."
wake:"[SHOCK]Wh..what [LOOK_UP][BLINK]happened?"
(to show more like the girl is waking up and is surprised to find out what happened)
vigorous:"I don't know how long [COUGH][ADD_TEARS]I can keep this up.. [HAPPY_MOOD][LOOK_UP][BLINK]but I need his cum.."{"style":"Thought"}
vigorous:"[HAPPY_MOOD]Mm, [LOOK_UP][BLINK][ARMS_HIS_LEGS]you like this huh?"
vigorous:"That's it, [HAPPY_MOOD][LOOK_UP][BLINK][SWALLOW]keep me sucking on your cock."
(You would want to add moods to show the girl is enjoying or disliking the actions being done to her. Also, Im sure you've seen a porn clip or dozen. You know a girl would tear up during a 'vigorous' session. This is why I added the tears to emulate real life)
But above all, download and review other peoples work to get ideas and to see the style or writing. Not just context. Triggers are the key my friend.