Toddler Behavioral Question: My daughter seems to always have her hand down my shirt.?

Totally normal. My boys were a combo and bottle fed, they always had a hand up or down my shirt. She is old enough to start learning where and when this behavior is appropriate. Like, at nap time is OK, but at the store is not. At 18 months she is trying to "stake her claim", and she wants your / skin to be all hers, and not share with anyone (even you, lol). Gentle reminders and distractions should help. I eventually got my boys to switch to rubbing/pinching the skin on my arms rather than my chest, it made me more comfortable (especially after 2 years of feeding, I really wanted my s back!!)