I am by no means an expert in AAC but a family I am working with (where child sounds very similar to your one) have just bought the pro loquo 2go app. Mum did a lot of research and spoke to some parents who have used it. They Seem very pleased with it, my only initial concern is I’m not sure you can reduce the choices to only a few on the page (although she may have not worked that out yet!). You can take photos and there are English voices. It is a recent purchase though so can’t give you a long term overview!
Will be interested to hear how you get on and what choices you make!