I-485, I am so confused. Please help.

Hi, My father filed the application for me using I-130 and I got the email from NVC this morning said that they are about to start processing my case. They asked me to fulfill DS-260 and pay the fee first. I called them right away to ask if I can adjust my status here in the US since I am working here under a legal working visa. They said I should ask USCIS and the answer is probably yes. I made another phone call to USCIS and asked the same question. The answer I got from them, however, was NO. They said I am not eligible to adjust my status in the State if I am over 21 years old. With that said, I have to go back for all kinds of stuffs and the interview.

Which one is correct??? Can I adjust my status here after my PD is due? Or I have to go back for this????

Please HELP!