CoolSculpting fat freeze. My skin was cold but not red enough. Does that mean my skin wasn't sucked by the machine properly?

The redness of the skin by no means reflects the effectiveness of the coolsculpting treatment.   If the machine does not have good suction it will alarm and stop the treatment.  I have seen a wide variety of skin color changes immediately following the coolsculpt treatment.  The important thing is was the underlying fat pulled up like a stick of butter, cold and hard requiring massage to get it to lie fat?  If you had this "stick of butter" shape prior to massage that is a much better indicator as to the effectiveness of the freezing of the fat cells than skin color.  

Immediately after a treatment, you can expect common side effects such as redness and firmness in the treated area. There can also be transient blanching and mild bruising. You can also experience some tingling and stinging. However, everyone is different, and not everyone will react the same to the treatment or experience the same symptoms. Your skin not being red enough does not mean that the tissue wasn't sucked by the machine properly. During the treatment, the tissue is being pulled and isolated from the muscle and blood supply, therefore it is completely understandable for the area to not be as red.