I agree with OP, Mamoru should be either a pediatrician or neurologist. The former because he's said to be exceptionally good with kids, the latter because of his own unique skills as an empath and experience with memory loss & brainwashing. (I could even see him as a therapist too due his empath abilities)
Ami is a bit harder... I don't think she's particularly great with kids (at least not like how Mamoru is, she's not bad though) but she is great with animals, especially cats. Maybe a veterinarian for her? I don't think she would work well as a therapist OP, she's too socially awkward and shy, plus I always saw her leaning into more 'hard science" fields.