Firstly, my condolences to you. I too, lost my cat last week and feel the same about my house being eerie...even though I have another cat in the home (I had two cats, but now I have the one surviving cat).
I am of the mind to wait on getting another pet, especially since your grief is so fresh. I know that in grief, people tend to make extreme decisions which ultimately become regrettable, or not something they would have done while in duress.
I am open to getting a second cat again, but I am going to wait until the grief subsides and it is the right time/opportunity to open up my home and heart to a cat that needs what I offer.
Sending you love,