Massive essay alert, sorry 
There are quite a few things that concern me. The main one is the poor eye contact and that she doesn't respond to her name, or me talking to her generally. The best way to get her attention is to sing her favourite nursery rhyme, but even then she will quickly look away.
She doesn't seem to understand any instructions at all, I suppose because she won't look at me to receive them. If she's crawling towards something dangerous and I shout "no" it's as though she can't hear me. Her hearing was checked yesterday and is fine.
If I'm really over the top and silly, dance around making faces etc she will think that's hilarious and will watch me for ages. The other good time to get her attention is when she's just woken from a nap. When I walk into the room she'll get very excited, standing in her cot almost hyperventilating with a huge grin on her face 
I try to leave her in the cot for as long as possible chatting to her and playing "boo" etc which again she finds very funny.
However she never tries to get my attention. She could play independently for an hour without looking for/at me. Not playing with the same thing though, she is extremely curious and always exploring.
There's no back-and-forth babbling. She makes a good range of sounds but never on the same day! And not whilst looking at me. For the last few days all she's said is "ooooo, oooooo, ooooo". Before that it was "mum-mum, mum-mum", and within the next day or two it will change to something else.
She will smile back at us and laugh if we are laughing, but won't copy any other facial expression.
She doesn't point or clap, but has just started waving back if we make a big fuss entering or leaving the room. However, she has also started waving at random other times - unsure whether this is arm flapping or if she is just interested in it because she's just started doing it. She bangs and taps things a lot, but isn't that fairly normal? She loves her rattles etc so maybe that's why she does that, I don't know.
I'd have a chat to your health visitor (on the phone probably). It's very easy, especially when not seeing many other people to get hung up on something and the more you look for it, the more worried you get-but that's because you're looking out for it, it doesn't necessarily mean there is an issue.
This is a really good point @Witchend, I do actually have anxiety and start to get very hung up on these things. Also DD has lived most of her life in our little living room and it's not really normal circumstances is it. On top of that I am a very quiet person and probably should have made more effort to talk to her. She did very well at Christmas when there were 7 people in the room, she just seemed very interested and not at all distressed. Even when I left the room for a bit though, so perhaps that's not a good thing.
I have spoken to the HV, and she said she would video call me next week to discuss what to do if the hearing test was ok (which it was). She is really reassuring usually but seemed quite concerned about this as there are a couple of red flags there.