In your opinion what was the purpose of showing amy's phone call with Sophie? For me it was so out of place to show that Amy will keep the baby… and is it a girl? As Amy was discussing name for a girl…
I have a couple of thoughts.
It may be as simple as – to make the story work and fill in the audience, they need Amy to talk about the pregnancy to someone who isn’t Dan, and for various reasons, there aren’t many characters who can fill that role. Realistically I think you’re looking at Sophie, Sue or Mike – Mike wouldn’t work for practical reasons (though the way Amy greeted him, I think she would have liked to go for a catch-up – she’s feeling lonely, poor thing), and Sufe Bradshaw’s health might not have allowed her to film at the time.
It may be an incredibly clumsy way of implying that Amy’s ‘over’ Dan and Sophie sleeping together, though if so, I find it rather unconvincing. It’s possible, I suppose that she’s made her peace with Sophie, for whatever reason – it stands out to me that, for the first time ever, Sophie was actually being helpful (she’s not wrong about Amy needing to make a decision) instead of pointlessly bitchy. Possibly, now that Amy too is dealing with an unplanned pregnancy, Sophie has let go of some of her resentment.
As for whether Amy knows if it’s a girl…it’s possible, I think? In the UK people generally find out at the 16 week scan – I don’t know if that’s the case in the US, but if you assume Amy’s 16-18 weeks along, she may have had time to find out. The only thing that strikes me is…Amy’s so jittery and uncertain, I’m not sure she would have taken any steps as concrete as arranging for a doctor. (With all the moving around she’s doing on the campaign, making appointments might be difficult). It seems like that would irrevocably commit her to the pregnancy, at least in her mind.