Hi Jen,
It's a while since you posted, so maybe you won't see this, but if you do, I just wanted to say that I sympathise with you. I lost my mum a year ago and still haven't been able to sort through her things yet. I can manage to deal with things she never got round to wearing, but anything I can picture her having worn, I just end up putting back in the wardrobe!
I think it was really brave of your mum to donate her body to research. She must have been a very special personto want to still try to help others, even after she was gone.
I understand that you need closure, but how about doing something like what an acquaintance of mine did, if you can't hold a funeral? They hired a hall and invited all her friends and laid on food and hung a big picture of her on the wall and played all her favourite music and spent the evening chatting with all those people who had known her and sharing their memories of her. It was a celebration of her life and your mum sounds like a lady whose life should be celebrated too. Just a thought, but I thought this might help you to feel you were doing something to mark her passing in a positive way.
Share with us here whenever you need to. Bast wishes, thinking of you.
Sandra