I don't mean to be rude or disrespectful. I don't know who old your kids are. Mine are 7 and 3 months. I'm of the belief that my kids didn't ask to be here. I CHOSE to have them. I'm blessed every single day to have them. I will protect them from whoever and whatever. It's my job, because I chose to have them.
My kids owe me nothing, but to be happy and to be the best people they can be.
Mother's Day isn't about cards and gifts. It's about your kids being allowed to show you that they love and appreciate you. Do you celebrate Children's Day? Do you even know when it is?
If you are really doing a good, no sorry, a great job at being a parent, you shouldn't feel the need to have a day to get cards or presents or have people tell you how good of a job you are doing. Because, you will know every single day that you're doing good.
As you can tell, the day mean nothing to me. I know I'm doing a great job with my kids. I get a hug and a kiss from my 7 year everyday. If I'm having a bad moment, I set back and realize just how blessed I am to have my family. Mother's Day was more important to my 7 year old, than me.
Have you ever thought that maybe it makes the other people who get cards feel good, too. By the way... Just because your sister has a dog, doesn't mean that she's not a mother. She's the dog's mother. I'm sure if the dog could talk, it would express the same love for your sister that you're kids express for you.