Dear Psyched,
What a tough time you are having. Don't ever worry about whats the right way or the wrong way to grieve for your Mom... she would understand how tough this is for you. I must have been about your age when I lost my Mom, a good number of years ago. I was lucky to have a close family and a Dad that really rallied for all of us and so I can't imagine how much tougher it is to feel that you are doing this on your own. Your Dad seems to have a very special bond with you coz you share an ability to 'feel'....don't forget that depression suggests that you are very in touch with your emotions. I know whats its like to worry about the parent you have left...thats only normal....but you are best working as a team. There will be days you carry him and days he will carry you. Also you have siblings, although you are estranged, you share a bond and hopefully they will prove to be some strength for you. The main thing I wanted to say is please believe that your Mom is looking after you...I promise you if you look for them, there will be signs and it will prove to be a great comfort to you. One of the last things My Mom said to me was 'I will stay with you as long as you stay with me'. Please believe she is watching over you and guiding you.
Good luck to you.