An additional factor is how much your parents’ opinion should, and does, impact you. Are you living with them? Are they paying any of your expenses? If they are still helping to support you, then the quid pro quo might justifiably include some conditions on their part.
Eventually, you’ll want to have chunks of significant time in one place. But for now, trying various positions on for size seems reasonable. You’ll gain leverage with your parents if you have a structured direction with timelines, goals and purpose. Sit down with them and explain your plan.
And is your idea of her dressing nicer just adding a few smashing items to her wardrobe, or for her to change her style from head to toe? If it’s the latter, this columnist has to ask what you’re after. To be more attracted to her? To show her off to your friends? To keep from being embarrassed by her MC Hammer pants? If the resistance is coming from who she is, then accept that she has the right to be that way. You have the right to decide whether that works for you. It’s your real selves that need to connect, not the ones that have undergone Extreme Makeover: Dating Edition.