My vet said that human fish oil was okay so long as it was true fish oil. I really do not remember what she said. It was a pain to prick the pill though as I would get it everywhere. It is a lot easier to get the ones for dogs. Just be careful that it is not too fatty. My vet offered to read the label to see if it was a good kind that I had been feeding. Maybe your vet can do the same.
Good luck on your decision to spay. Maggie was just under 4 lbs when she was spayed and did really well. She was out of it for the first couple of days.