Gifts

I love my birth daughter with all my heart, and I just want to spoil her to death. Every time I see a cute little outfit or a toy she would love I want to buy it for her. However, I already know her adoptive parents aren't super comfortable with that. I see why, they don't want their kids to just associate their birth parents with gifts. It's also not fair if I buy both her and her adopted brother a bunch of gifts if his birth parents and her birth father don't or can't afford it. I do always bring a gift for the brother if I bring one for her because I love him too. I also don't want the adoptive parents to feel bad or obligated to get me a bunch of stuff just because I do that for the kids. We just do Christmas and birthday gifts. My question is how many gifts are appropriate? I've got about five things in my closet that I've bought for her because I know how much she would love them. But I don't want to go overboard or make her parents uncomfortable. Her birthday is coming up so I'm trying to decide what to do. Adoptive parents, how much do you think is excessive gift giving? I'm not trying to buy her love, and I really hope it doesn't look like that.