Thanks very much for your reply, Joseph!
Yes, maybe it is quite ‘off script’ 
I usually end up getting what I want in the end, but it’s a struggle getting there sometimes. (Probably all good practice for my Portuguese). The local cafes / pastelarias know my quirks by now too, which makes it easier.
I’ve had fun ordering coffees in the past.
I had another instance of getting two coffees when I asked for a ‘café abatanado’ (even though I was just at the cafe by myself). That ‘café’ really is redundant in this context.
Another time I feel I really irritated the guy behind the counter by continually saying ‘mais cheia’ when he presented my abatanado!
I don’t think I will ever “go native” with my coffee choices. Espresso makes more sense to me if you are drinking many a day but I just want one or two coffees a day that I can savour.
I’m also quite happy ordering a meia de leite after lunchtime 
If I get deported from Portugal, you’ll all know why!