Animals are members of our family.
I got my first cat (since I was a child) just after my divorce from my son's father about 7 years ago. My son and nephew were playing with her in the bedroom when they came out holding her with a her eyes and nose bloody. On another occassion, not long after my nephew was allowed to return to my home MUCH later, I saw her dragging her tail. Now, anyone who KNOWS cats knows they don't drag their tail.. almost EVER. (I've never seen it before or since.) The story finally came out in both cases that she was being tossed from each boys lap when the eye/nose issue happened and put her claws out to fight back, when my nephew punched her for hurting him. (The cat was doing what came naturally.) The tail incident also came back to my nephew, who was not allowed to play with the cat (kitten still). She had been trying to get AWAY from him and went behind the sofa, at which point he grabbed her by the tail. She sunk her claws into the carpet, needless to say, and he pulled until he got her out, dislocating her tail.
Her eye and nose cleared up quickly, but I had to take her to the vet to deal with her tail. Doc was able to put the tail back, tho he wasn't sure if it would 'take' because it came dislocated at the very base. Chances were slim it would heal, in which case, I would have had to lobbed her tail. That very day, I told my nephew, "Go HOME, before I do something I'll regret." (He lived across the street.)
I was NOT happy. I'd only had her a few months at the most. As much as I love my nephew and son, I was sooooooo furious that I told them both that they had their punishment (no contact for 6 weeks) would be MUCH worse if I had to lob her tail.
In answer to your question, you loved your cat. No doubt about it. The timing of getting him on Mother's Day has very little to do with your response to the loss.
Give yourself time to get past the loss. You are not responding out of character at all. If you still miss him terribly, there is nothing wrong with finding another cat/kitten to fill a void. No, a new one will NOT replace him or get rid of the pain of the loss. But having another kitten around WILL give you joy. It's their JOB!! (as if a cat can have a JOB).