The same thing happened to me. My 11 month old 3.5 lb yorkie got pregnant from my 5 lb 11 month old maltese. I took her to a great vet who did an ultrasound so I would know how many puppies there were. He told me "the more the better, because they will be smaller". He too, thought she might have problems, but he just told me to be sure not to leave her alone during the last weeks, (ever) and to know where my nearest emergency vet was.
I use to breed Doberman Pinchers, but never small dogs, and it had been 20 years since I had whelped any puppy. I was scared to death, so I did everything the vet said. I even took her temp twice a day until she gave birth. I also enlisted the help of my husband and 29 year old daughter who was much more calm than myself. I think being young can be a good thing! To make this long story short, I was expecting 4 puppies, (that's what the ultrasound said) and to my surprise, 5 appeared. The mom was great! She knew exactly what to do and had no trouble. 2.5 hours after the 5th was born I took her to the vet to make sure it was the last. She did well, the pups did well and it all ended happily! Because the mom was young, she lost interest after 7 weeks, but that's plenty of time.
Don't panic, you can do this. Just stay calm and be prepared for an emergency. Enlist the help of friends and family, it does help! Know where to go. You can do it!
GO TEAM!