Mother does not want to stay with me

I can understand about your mom's homesickness but still i think your parents can behave a little maturely, after all its 5-6 months and since they have committed your mom should be happy to perform her duties and keep you happy rather than brooding all time and your Dad should assure her that he is fine and can manage well with the help of your sis and grandma.. if this is the environment then everything will be fine..

But one this is certain you cannot force her to be happy it should come with in her... so do according to her and book her tickets and don't fight or argue with her, make her stay pleasant even if is for a short period after all she is feeling guilty because she is not there with your dad that to when is not keeping so well...

Prepare your self to tackle the task of taking care of yourself in your post preg days . I have heard number of cases who have gone through pregnancy & deliveries without parents help.. so be happy at least you have your mom's help even if it is for shorter period.

Have positive attitude be happy and keep your mom happy.

 

Firstly Congrats!!!
I suggest you get help from ppl who are willing to help you than from ppl you force to help you out.
I hope I dont sound blunt, maybe at this point your mother feels you are less of a priority.
So get help from your FIL and MIL and send your mom back, so that everyonez happy