Im so excited writing this, 'cause I believe I know exactly what you didn't do and what you did wrong.
First of all, get this into your head: You were INCHES away from having sex with this girl, or at the very least kissing her.
I have several points to make here:
1: You're not great at german, and most germans does not care to learn proper english (arrogant bastards), and you have problems getting from a kiss/phone number to sex.
The last week I really got into the 4-compendium book written by 60 years of challenge. His methods is EXACTLY what you should be using. It's all escalating furiously fast, keeping eye contact, be persistent, and shutting the fuck up most of the time.
See how that fits to you?
a) You've got problems getting to sex /// This game-style is probably the most sexual one.
b) You've got a language barrier due to english/german skills /// This game-style is probably the most non-verbal one, it's all about making her talk so you can seduce her with eye-contact, seductive smiles, and eventually caressing her.
Okay, some specific situations this night I wanna talk about:
2: Even though it worked, you shouldn't have started dancing with her fat friend. HB9 knows you wanna get with her, and not her fat friend, women are not socially stupid. So by dancing with her fat friend, you're actually just showing the HB9 that you're too insecure to go directly to her.
but it worked!!! - Yes, but you would've created more sexual attraction from the HB9 if you had done my above suggestion.
3: You do some seemingly clever cocky-funny thing and comments that she's gonna taste horrible when you kiss her, which is both good and bad. I'm assuming you said it playfully and with your goal being her laughing about it. However, this comment would've been absolutely golden if you had said it very seriously while keeping eye-contact, and with a little seductive smile on your face. This is basically the same problem as with dancing with her fat friend first.
You said the comment while in self-defense-mode. You said it half-jokingly 'cause then she wouldn't turn ice-cold and reply "we're not going to kiss.", and you wouldn't end up getting hurt. SHE KNOW THIS! She knows you want to kiss and fuck her, but she's thinking "apparently he didn't dare admit it, because he is protecting his feelings.." - Not sexually attractive. ESPECIALLY not in a situation where she has actually
taken your hand and lead you with her - This girl wanted to be fucked!
If you said it the seductive way I suggested, you would've have created more sexual tension, and she would be more turned on, and thus very open to the idea of having sex with you.
You might have been able to recover from the 2 above things and sleep with her that night anyways, but these two last things I'm going to mention is dead seriously sexually
catastrophic:
You were ashamed of your boner?!
Say this with me:
I'm a sexual being, I'm a sexual man! I have a boner! I not ashamed of my boner! Because if IM ashamed of my boner, why the hell would SHE touch it?
Rub that boner all over her ass cause, again, she is not stupid. She knows that when she rubs her ass on your cock, its gonna get hard, and she's going to feel it. She wanted to feel your boner! That's a good thing!
The fact that you were awkward about your boner really turned the sexual tension off between you and her.
But to finish the last sexual tension between you and her, you actually GIVE UP after she makes her standard ASD response "I dont know you well enough". Persistence is sexy, your response should've been looking her seductively in her eyes, smile, and then after some seconds leaned in and go for it again. I guarantee she would've kissed you. I guarantee it.
Instead of just reacting cool, you do the worst possible thing: Act depressed and hurt - you actually hung your head! This is your biggest mistake all night. One of the most important things I've learned about game is: Women loves to reject you, to see how you respond to it. They do it all the time! You can call it a shit-test. The point is, when someone rejects you - you NEVER EVER EVER react to it. You simply smile, maybe break eye contact off quickly, and then you can go for it again right away, or you can wait some minutes just to be absolutely sure.
Advice that will change your game radically positively:
Read "60 years of challenge", especially the "Fearless Relentless Escalation" and "Women Ignition" compendiums.
I hope I wasn't to harsh on you man. You actually did great. If you notice what I've read, it's mostly the same corrections I'm making, meaning you only need a little bit of game-polishing on that area (50 minutes of reading, really...), and then you can officially land HB9's

- So please realize that you are actually very close to have great game!
PS: No I'm not a paid advertiser from "60 years of challenge"

, I just really thought his methods applied perfectly to the last inches you are missing.
Have fun!