Parents of Autistic child need advise

hello parents, lets start by saying I am a child development major soon to be teacher.... It is not my job to diagnose chilcdren put bring up in question that there might be something.....

So heres the issue; I have to daughters a 3 year old (soon to be 4 in June) and a daughter that turned 1 in January..... every child is different in development I know that. My oldest was really quiet and calm growing up I would say I had the perfect baby; now when it comes to my 1 year old its a different story.

My 1 year old is hyper and wild and really funny, very opposite of my 3 year old, now my 1 year old will yell for no reason amd laugh about it. But when she cries its for no reason, I am sorry to say but I just can't get her to shut up lol.

I am worried for my 1 year old she seems happy and everything but when she cries she cries for no reason, for example shes tired but then she wants to play and I will try to put her to take a nap and she will simply cry even if I am laying with her. Next thing you know she will calm down and go play like nothing happened.

Another example is she will not let me put her down for anything even if shes feed and changed and happy, I am just wondering if I am dealing with a normal child or shes autistic.... she's everything I wanted but I am trying to figure out what is wrong with her..

Now when she gets angry she gets angry, I will bring this up with her doctor she has an appointment next month but like I was saying when shes angry she will start crying and she will not breath there has been a couple of time where she will turn purple on me and almost fained. When she gets like that theres no way of bring her out, I tried hugging her and soothing her and try blowing air into her face (lightly).

I honestly need help, I feel like I am doing something wrong. Seeing my two girls playing just makes me super happy but my youngest really worries me. Can anyone please help me I am really confused