I don't know the difference between various blood tests you can have. Perhaps Google them to see? Getting ahead may be good, as you will be more informed instead of having to make snap decisions on the day.
I think the younger and first pregnancy applies more to one condition than the other. One is more likely (though both are rare) when younger and with first pregnancies and the other is more likely the older you are and more pregnancies you have had. But this is your first successful pregnancy, so I don't know where you would be on that front, whether this would be classed as a first pregnancy because it's the first successful one, I don't know how far you got with the others or if it makes a difference.
I am so sorry your mum was less than supportive. I guess it's a defence thing, she probably is detaching a little 'just in case'. I know that's awful and isn't what you need from her. People react differently to difficult situations and when it's someone so close to them, sometimes the worry is too much and they automatically distance themselves. My mum does this.
However, she also does similar to your mum too, like she said I shouldn't be with my husband because apparently I would walk all over him, she said she didn't think I should take on his daughter when we decided to have her live with us because her mother wasn't looking after her, she said the same with husband's son after his mother passed away and said maybe he should live with his grandparents instead! I can understand this and how it makes you feel. Our parents are meant to be supportive, whatever the situation.
Is there anyone else who can go with you next time? I think it's a good idea if there is, because it will probably be overwhelming and a lot of information to take in.
But you know what, I know we can't be there with you, but everyone here will be here to support you every step of the way, always