I would say at 6 months pregnant now is not the time to be buying and selling a house, its very very stressful.
Talk to us, tell us exactly what the problems are. In a few months time when the baby is here can you re asses the problems and see if they are still as big.
You say there are no family or friends near by, have yu contacted your local childrens centre? there are some great bump and babies classes out there, you come under the catagory of 'young mum' and there are some fantastic classes too, I've been to them myself and made some friends that way.
Join an antinatal group on here and have a look at the local section, I'm a local ambassidor myself and there are lots of meet ups, buddy benchs etc going on.
I've had antinatal depression and its not nice to feel so low before the baby comes, I'm not saying that what you have but I know how you might be feeling.
When I was pg with dd1 I lived 80 miles from family, had no friends and really struggled. But the thing I lernt is only you can make the diffrence. We can all give advice on here and say put the house up for sale now or go along to sme groups but unless you take the advice, stop crying and take steps to improve your life for you, nothing is going to change.
Good luck