Potty Training

Me and my boyfriend been together for almost 3 years now & have a 3 year old daughter ( not biologically mine ) . We're trying to potty train her . You might be thinking why did you start so late etc . She ( our toddler ) was abused by her biological mom so she had to start all over with us from walking , talking , feeding herself etc . She's came a long way but back to potty training ; Sometimes she let's us know she has to potty , sometimes she'll pee in her pull up even if we ask her if she has to potty . Any advice as to what we could do to help her want to go to the potty ? It's frustrating sometimes because she's actually pretty smart and knows how to use the bathroom but doesn't always go to the potty .