Recalls ("come") are tricky! Sometimes we break the word. If you think Shivon may consider that word something that is optional to listen to, change it! You can use "here, now, you-hoo, side, front, spagetti" ... you get the idea, any word can (to a dog) mean 'come'
Once you decide on the command word... treat like crazy... you know how your dog will instantly come to you if you open the treat cupboard? or bag... well, that the response you will get... if they get treated EVERY time. It is explained at length here, in a few other threads, browse around, there is so much good info here to read.
The short answer for the crawl is... from a "down" slowly lure (move a treat) in front of your dogs nose. Give treat... move an inch at a time treating (without raising the expectation) until Shivon needs to creep... if your dog starts to get up instead, you've gone too far too fast. Only work for 5 or so minutes, keep it fun and quit before you dogs gets frustrated.
Welcome aboard... you've found a terrific, brilliant bunch. We do a lot of positive.clicker training here. We try to look at things from the dogs perspective. We encourage and learn , just like you!