Harry, I'm so sorry you're feeling low. Please don't apologise for saying how you feel! We're here through all of it - the good bits and the bad. I'm guessing you and your sister aren't particularly close? Could it be worth giving her a ring and opening up a little to her? Or a friend that you were incredibly close to, that you could reach out to? Or your dad? I'm so sorry you don't have your mum to reach to. Even though they may not be particularly forthcoming with excitement towards your pregnancy themselves, I can bet that if you were to explain to them how you were finding it difficult being alone, they'd rally round after you. I can bet it's highly likely they just haven't really thought about it much with you being further away but DO care and certainly wouldn't want you feeling this way.
Also, have you joined any pregnancy exercise classes or are they not really a thing where you are? It might be a way of meeting other women in your situation who could become friends. You're going to need a network of support once baby comes and it's important you don't go through this alone (obviously you have your OH but I'm assuming he'll be out working once baby comes?).
The third thing I was thinking of was speaking to your GP if all else fails because as you say, you don't want this to spiral and from what friends have said, this is the easy bit and once baby comes it can be incredibly lonely and isolating, even with a team of support around you.
In terms of your fall, I'm pleased to hear LO is still wriggling around in there as normal but speak to your midwife if you're at all worried. It's such a shame nobody helped you 
where is the goodness in people?!
Anna, ooh it'll be interesting to see if it matches up with girl, haha.