It's kind of silly to think you aren't meeting your child's needs (practicing AP) if you do or don't do something, or use this or don't use that.
I mean the entire point of attachment parenting is to respond to your child's needs and every child/family situation comes with so many variables.
We never used a high chair just because it seemed like a waste of space in our teeny kitchen. DD has a booster seat that has a detachable tray, I guess that's pretty much the same thing as a high chair.
We used sippy cups and straw cups. My DD is 3.5 and she still has a few random sippy cups that she loves. She calls them her baby cups. Doesn't matter to us, it's not like a pacifier or something that could be harmful dentally speaking. She knows how to drink from a regular cup without a lid or straw just like an adult too.
We have cats, and I've found that sippy cups are important--DD likes to keep a drink of water by the bed now that my milk has dried up during pregnancy. If it isn't spill proof sure enough a cat will spill it in the middle of the night, or a cat will try to drink out of it, or get fur in it--yuck! (I keep a stainless steel bottle on the night stand for myself...)