Junior dev: breaking down tasks

Hi! I am a junior web dev, mostly FE (albeit with 10 years of experience in a different field, so I'm not straight out of uni) working in a relatively small company. We're working on a new FE and I find myself struggling with breaking down tasks into smaller pieces. My Jira ticket is basically a link to our Figma page view without any steps/analysis done whatsoever. The views handed to me are quite straight-forward (eg registering forms, list views, data tables) and I can always check the existing version of our product (written in a different JS library) to find the correct API endpoints and so on. However, sometimes I find myself working on small (and maybe unimportant) details for way too long. I've been working as a dev for 5 months, I have no idea how long a task should take, and sometimes I find myself jumping back and forth between different things. I also happen to have ADHD, which makes organization and focusing difficult and many things that come naturally to my colleagues are a struggle for me. I love my team, they are very supportive whenever I need technical help and I can ask a lot of questions, but at the same time I work on my own a lot, I don't have 1-on-1 meetings and I don't get much guidance outside of code reviews. It seems that they are not experienced in onboarding junior developers (I don't think they've had many juniors before, our devs started the company and have been doing the work since the beginning themselves so far, we don't have a project manager either). I am not sure how to ask for help in this matter either, as it is not a technical thing, rather than work organization thing.

What's a good practice for experienced developers to start working on a task? Do you make a plan? Write down which components you already have/you need to use? How detailed are your to-do lists? Help a sister out and share your tips, I really love my job and I don't want to get fired. Thanks!