I think that "independent" and "self-directed" in the context of a PhD aren't exactly the things you're talking about here. I don't at all want to minimize that having executive function issues is going to make it harder for you to get through the sheer amount of work that it takes to do a PhD in natural sciences. But being self-directed means things like you finding something novel you think should be looked and putting a case together so that your supervisor can apply for funding so you can do the thing you're interested in as well as the stuff she's interested in. That's the thing that lots of people who are good at passing exams in undergraduate never make the leap to being able to do, and you clearly can.
It's also a little bit to do with figuring out how you can reshape your life to make it possible to do put in the hundreds of hours of labwork you need. And later, how you can make yourself put it altogether in a novel-length thesis, finding a way to get enough writing done even with very little in the way of external rewards, encouragement or feedback. The fact that you break down tasks into small steps is an advantage, not a problem, for being a "self-directed" PhD student: you're good at planning your own experiments, including working out how to make the timing of something that needs lots of timepoints fit in with the rest of your life.
"Independent" in this context doesn't, certainly shouldn't, mean that you do all this without any support from your friends and from professionals if need be. Independent means you're making decisions about your research, both detail level decisions like what time should I start this experiment so the samples are ready when the instrument is free, and high level decisions like what's the best experiment to find out why there's an anomaly in this data. I get the impression that you're really quite independent in those ways, even if you need help with getting out of bed and dressed and into the lab so you can in fact start your timecourse at the time you decided would work for you.
no subject
It's also a little bit to do with figuring out how you can reshape your life to make it possible to do put in the hundreds of hours of labwork you need. And later, how you can make yourself put it altogether in a novel-length thesis, finding a way to get enough writing done even with very little in the way of external rewards, encouragement or feedback. The fact that you break down tasks into small steps is an advantage, not a problem, for being a "self-directed" PhD student: you're good at planning your own experiments, including working out how to make the timing of something that needs lots of timepoints fit in with the rest of your life.
"Independent" in this context doesn't, certainly shouldn't, mean that you do all this without any support from your friends and from professionals if need be. Independent means you're making decisions about your research, both detail level decisions like what time should I start this experiment so the samples are ready when the instrument is free, and high level decisions like what's the best experiment to find out why there's an anomaly in this data. I get the impression that you're really quite independent in those ways, even if you need help with getting out of bed and dressed and into the lab so you can in fact start your timecourse at the time you decided would work for you.