This is ridiculous. Some of you are acting like if you don't say exactly the right thing at exactly the right time in exactly the right way to a girl, then you are screwed. THAT IS AFC. For even thinking that way, let alone acting on that thought process. Man some of you put women on such a pedestal its sickening. You really think you have to be that perfect around a women? If you do, you have problems. Deep seated insecurity problems. What did people do for 50 years when texting and emails weren't around? Left a message just like that on an answering machine and things got along A Ok.
What the OP did was fine. There is NOTHING wrong in what you did. You called her instead of texted, which is great. You acted interested, but didn't go overboard, and you asked her out. What is the big deal? Nothing. What you did was perfectly normal. The fact is if she was interested, she would or will respond and either go out with you this weekend or make plans to another time. She is not going to listen to that voicemail and say to herself, "oh, OP didn't exactly word that VM right, plus what an AFC to even leave a voice mail, what a loser". Well, she might say that if she is a crazy person. But assuming she isn't....Of course she didn't say that to herself. No reasonable person would.
Keep on keepin on OP. You're fine other than stop over analyzing and getting bad advice.