potty trained but having accidents

Hi there.... I would say if she is staying dry through the night then it is unlikely to be a physical problem that the doctor can help you with... GP's usually don't start considering this as a medical problem until a child cannot stay dry at about age 6 or 7.... it is more likely... as you've suggested... a behavioural thing.... eg being too interested in play to recognize that she needs to go (or want to stop what she is doing even if she does recognize the need).

Is she in pull-ups during the day or in regular underwear? If she is in pull-ups I would recommend getting her out of those as they are so similar to nappies (in terms of their ability to quickly remove any moisture from the surface of the skin) that it is not helping the child to learn and connect the physical feeling inside of 'needing to go' with the discomfort of wetness if they do not make it in time... If you want to go somewhere in between pull-ups and underwear then you can get cloth pull-ups which will do the same as regular underwear but are a bit more forgiving of accidents.

I would also suggest, if you like, using rewards... like stickers for her to wear or stars on a chart (and of course lots of verbal praise), for when she successfully uses the potty... that will provide her with some motivation. Try your best as much as possible to ignore / give no attention to the accidents... just quickly clean her up and carry on... do not react negatively to that otherwise she might start to fear going to the potty altogether... just go with the lots of praise when she succeeds. 

This sort of thing is super common and I would try not to worry too much... she will get there with it!.

If you still need more advice... your health visitor would be a good person to talk to about it or many community children's centers / sure start etc have advisors that will be able to help you.

Good luck!