I can understand why you're worried, but honestly, at 2 years 4 months, some children just take longer to warm up in group settings, especially when they interact well at home with family. That said, the teacher's feedback about eye contact and not speaking in school is worth taking seriously, so I wouldn't wait until 3 years if your gut is telling you something feels off. It would be good to bring her to see your PD now and share what the teacher observed, because early assessment and support really does make a difference if she needs it. Whether or not it's autism, a professional can give you a clearer picture and put your mind at ease.