I also drank on phenibut in college. I take pity on a socially anxious young man. Here is some free advice:

Do not treat her like she's precious, treat her like she's bored.

Act recklessly with the knowledge that you're probably going to fuck it up, because you're 18, and you have to trial and error before you get good.

"5 dates" is way more than enough to be getting physical. If she genuinely likes being around you/you're making her laugh then she is just patiently waiting for you to do something.

The next time you're alone in a room with her and she's feeling vaguely happy, look at her lips. Just autistically fixate on her lips. Maybe you're in a car or your dorm room or something, stop treating her like a person and just look at her lips. Allow yourself to be distracted.

IDK if you've ever kissed a girl, I hadn't at 18. But my advice is don't try to be "good" at it just be curious. Don't be afraid to hold her and grab her like she's a big human doll. Use her for your pleasure. The same way you did when you were dancing.

You will probably be awkward and fuck it up, because you're 18 and have no experience, but that's OK because you gotta fuck it up over and over to learn.

Life is long. Being a little drunk helps. Phenibut is unsustainable.

Review:

1. Have another fun date/excuse to be together

2. Take a shot or something

3. Take her somewhere private

4. Look at her lips

5. Kiss her, do not be precious/afraid to fuck it up, she is one of 4 billion girls (and unfortunately that is the mindset that is optimal for dealing with them, as far as I can tell.)