Bom dia, Dave.
I think the word "amigos" is a collective form of address, so that if you are talking to both men and women, you don't need "amigas"
My Portuguese is quite good.
I know it's a bit of a trek, but there is a huge Brazilian community in London, and they have lots of events. I've been to samba festivals at the Royal Albert Hall, and it's been almost entirely filled with Brazilians. And ... they are SO friendly.
Try getting along to a few of those.
E ... boa sorte.
Com os melhores cu mprimentos
JJ