One of the problems I see right off is that your lil' one was taken too soon from her litter mates and mother. Reputable Breeders will know why it's important for their litters to not be going to their new families until the age of at least 12 weeks old.
Unfortunately, your Breeder did not follow this practice and now you are to assume the role of mother & litter mates. It will be a a lot of hard work still to come but, if you can give the time and attention that your new pup requires you will get through this.
You are not alone, I was in your shoes when I purchased my first Yorkie way too young. It took a lot of commitment and devoting myself to Bella. For at least the first three months, my life revolved around her 24/7.
Potty training was accomplished but as many will attest, there will always be oopsies from time to time and sometimes daily. It can be as simple as a missed squat and only getting within an inch of the pee-pad.
I think the best advise I received was to keep Bella's world small. So, when I could not be with her, I would use an infant travel playpen. I sectioned one half for her bed and toys and the other side for her pee-pad. It helped her concentrate on where it was without having to search through an entire house for the pee-pad.
I used a child gate to cordon off one room at a time. If I went into a room, a pee-pad came with us and the gate went up.
While I was working away from home at the time, fortunate for me & Bella I worked only 2 minutes from home. So, I had to come home twice a day to check on her. My lunch hour now became divided. I was always coming & going in the beginning.
Meals were scheduled which was paramount to be able to time her poops. After meals, I would take her outside and voile' most of the time, I could time it just right. Other times...nature didn't follow my program and I would find a tootsie roll...sometimes on the pee-pad and other times not.
What I am trying to say is, get set for a long haul and whatever you do...do not double your trouble right now by assuming your pup might need a playmate. All you will accomplish is to double the frustration you are going through right now.
Patience and being consistent is key and oh yeh, putting your life on hold for the next couple months.
