I consider myself an Agnostic, so I don't have an answer for that. But I am so sorry you have experienced the loss of your loved ones.
I don't believe in "Heaven" as a particular place, either - although I do think there may be something more than we know of that happens after our existing bodies pass on.
If you want to explore the topic a bit more, an interesting book you may want to try to find and read is called "Life After Life" by Raymond A. Moody. It consists of peoples' experiences with death (i.e., people who were considered clinically dead, but subsequently survived).
It is out of print, but you may be able to locate a copy at the local library or through a used bookstore (online or actual storefront).
