Legumes and soy products are a good source of protein. I swapped milk for soy in my breakfast and tea etc and I eat legumes 3-4 times a week if not more.
Wholegrains are also high in protein, so wholegrain breads, pasta etc.
I eat a TONNE of yoghurt and it hasnt affected my weightloss. And by tonne I mean up to (and sometimes more than) 600gms a day. I have natural low-fat plain yoghurt and usually mix in some frozen berries and have that for lunch.
My total calorie intake through a normal day is between 1200 and 1400.