Boxer/Bulldog mix puppy potty training issue...?

I just got a boxer/bulldog for xmas for me and my son. I'm enjoying her and watching her and my son play. I'm very strict with the potty training. She is getting there but it seems like every 5-10 minutes she is peeing. They are just small drops like the size of a quarter to a dime....she is 8 weeks old utd on shots. Do you think this is happening because she is so small (weighs about 3lbs she is the runt of the litter) that her bladder is small right now so she has to go a lot or should I look into taking her to the vet for a possible bladder issue or UTI?