Generally speaking smaller dog usually have smaller litters even as small as one while larger dogs tend to have much larger litters such as 5-9 or more. My rottie had 11 this last time.
Usually trembline is an indication of pain and likely means that she is still in active labor. She will have minor contractions after all the pups are born but in most cases doesn't lead to bad trembling. Pups that are in the birth canal too long usually do not make it and it can indicate that the pups are too big to be delivered. Since she isn't eating yet, if these contractions have continued, I would have her seen by your vet to be sure there are not more pups.
Remember that small dogs that are not eating and didn't eat the afterbirths may experience a drop in blood sugar levels leading to hypoglycemia and trembling due to seizure activity. Put a drop of pancake syrup on her gums to be sure her blood glucose levels stay up.
Other things you need to watch for is eclampsia. This usually happens 2-4 weeks after birth but can happen earlier if the mother was not on puppy food during the pregnancy and in some cases even if she was. If your dog is experiences muscle weakness, muscle spasms, tremors or seizures, limb paralyses, she needs to be seen now as it is possible she has eclampsia. Calcium supplements, Tums, cottage cheese or goat’s milk may help, but it might not reverse the symptoms quickly enough.
Here is a site with more information on this.
In your dog's case, I think I'd err on the side of caution and have her seen if she still has trembling and hasn't delivered a pup.