My husband got me a lab/pitt mix puppy for my b-day about 8mos old. she is trained 2 potty outside but goes?

way 2 much(like 5 times daily) Unfortunately I am only able 2 take her out about twice a day. Consequently, she goes inside several times a day(especially overnight). On average about every 3 hours. My grandma knows alot about animals and says she is just 2 young to hold it. Is this because of the dogs age? If so how long will it be before she goes less?