I think it is perfectly natural to feel the way you are feeling. It is natural to want the love of one's parents and siblings. It's difficult to move on from those developmental years and create a present that we can feel good about. If what you say is true then you just have to consciously create a new life. Do you have any interests? It doesn't have to be a big deal. Here on this site are lots of social groups that share personal opinions and insights on enjoyable day to day activities. I've greatly enjoyed the club about TV shows. There are two book clubs that I find really fun. The people in these clubs are sweet and smart and always kind. Look around your community. Do you have a community college or community center? Do you have any religious or spiritual leanings that you might like to explore? I've read in many places that one's work place is becoming one's new family. I'm not sure how far I would like to buy into a workplace family because people move around so much but a church or community center would be much more stable. Volunteer your time to good causes and stay as busy as you can. It's a wonderful feeling to be useful and this can be completely fulfilling. Stop chasing after what you cannot have and see what is possible.
I hope you feel better soon and keep us posted on your exploration.