I thought I'd lost a lot of people and though I've never counted, your list sounds longer. I like to believe they are all still with us in some form or another, especially those dearest to us. I doubt that idea helps now. I am going through my own recent grieving process, and what seems like a perpetual grieving process over many years. I don't know if you'll find the perfect counselor though there are good ones out there, I had a great one used guided meditation and hypnosis training who I no longer have access to. Perhaps look for those who focus on PTSD and somatic techniques as well as grief, or consider acupuncture if you are open to it. I used that for a particularly traumatic loss, I went to a school for 5 element provider though if you decide to go that route make sure it is one who uses more gentle techniques, many are not. Try to remember to breathe and go outside in nature if you can, it can be very soothing. Allow yourself to cry when you can, get the pain out. Nature and standing or sitting barefoot on the grass is really good for depression. And of course know that there are many in this community who support you. Being alone, is not so good. Sending you caring, peaceful energy. It is sometimes harder being the one that is still here. I try to believe there is a purpose for that.
I hope that some of these ideas help you. It sounds like you've been down this road before so perhaps you've tried them all. I hope you are able to find your way and not fall back into that depression you spoke of in your past. It's okay to be grieving the loss of your furry friend, sometimes we cry most when we lose those that give us unconditional love. I don't think they want you to be so sad now. I am trying to be strong and remember that myself. And remember, there is nothing wrong with you, what you are going through is actually a normal part of grieving at least so I've read, so I hope you can try to not to be too hard on yourself. 
Edit history
= new reply since forum marked as read