First off, do you still behave how you did at 12.5months old?
Nah, didn't think so. Don't worry that she's going to behave like her toddler self for the rest of her life!
Secondly, attention is a human need especially for a developing child, so if she were attention seeking that would not be "naughty" it would just be a piece of information to tell you that you might need to adjust your behaviour to meet her needs better. But in this case she just sounds like she's curious about her world, which is great.
She cries if I try the cup.
I don't have an opinion on whether it's right or wrong to persevere with the change, but just as an observation for the future - she's crying in that scenario because it's different to what she's used to. Not because you're doing something terrible or harmful.
How does change from the familiar feel to you? Uncomfortable, worrying, confusing, sad, exciting, unsettling...
Crying is how she communicates that to you. It doesn't mean you automatically have to reverse what you're doing. Sometimes it will be about letting her adjust and feel secure that this new change is ok and safe because you're showing her that by how calm and positive you are (rather than anxious and worried because she's upset).
I think you're overthinking a lot. Don't be so hard on yourself. And also, don't forget that her brain is still developing - she isn't experiencing the world the way you do, she doesn't have the same brain processes as you yet. When she was born she didn't have any concept of existing, of being a being, of being separate from you - it's not that she was born with a miniature fully developed brain like yours but just didn't know how to talk yet. A baby's brain is just reacting to stimuli and over time becomes more sophisticated as she has more experiences of the world and builds pathways based on those experiences. Pulling at curtains and finding out what happens and how it feels when she does that is part of her brain development!
So maybe worth just pausing and reminding yourself of that when you find yourself thinking of her /treating her as if she were a miniature adult cognitively, attributing motives that she's isn't cognitively capable of, etc. Your role as her parent is to help her brain develop healthily with the pathways that will set her up for her future life. Worrying a bit less will help you in that.
Your daughter sounds lovely and you're clearly doing great apart from all the worrying! 