Re: I could use some advice...
I personally don't think it is a big deal, but since you are bothered by it you may want to talk to her.
I have 6 nieces and nephews, and 4 step-nieces and nephews, and I don't call or send gifts for any of their birthdays. I have a brother and two step sisters, and DH has two brothers and a sister...none of them call or send gifts or anything for my girls' birthdays. We are all close but I guess it's just the way we are; no one is offended.