12 weeks 6 weeks adjusted

My daughter is six weeks adjusted, she still doesn't smile, only like once every couple days she'll smile and it takes sooooo much talking and singing which I do all the time anyway but it only works like literally once every couple days. She doesn't hold her head up much still even though we do tummy time everyday! She doesn't follow us with her eyes much and actually she doesn't look at us much at all. She'll look at us when we're feeding her, or when we aren't looking at her. But when we start talking to her and stuff she usually doesn't want to look at us, she'd rather stare at the wall. I'm completely fine with my little girl developing at her own rate but is it to early to start thinking about maybe autism. I'm naturally a worrier...unfortunately. I'm just wondering if anyone has older preemies that experienced anything like this, or if anyone maybe has a child with autism and if any of this sounds familiar. I love my baby girl no matter what! Just thought id see if any of you woman have any similar experience.