Anything new, like moving from pen/paper to digital device is going to feel really awkward at first. There are brain-level physical reasons for this; the simple explanation is that new neural pathways must be created (we call them habits), and that takes about 30 to 60 days with daily, focused, and intentional practice. Not something our ADHD brains are prone to, but certainly capable of (especially when properly treated).
In terms of apps that help with task management, I’m certainly on that journey myself. I have been looking at Trello, but I find myself unable to decide how to best organize it to fit my needs. So far, I just use the plain-old to-do list app that came with my phone (an iPhone). That seems to work for the important things, but some of the lists just grow and grow with things I simply don’t have time to do, and then that overwhelms me and makes me not want to use to-do lists.
There are a few articles on this site regarding apps the help organize life, etc. Search around.
Any life coach/therapist/consultant etc. that’s worth employing will be expensive, but there are different levels of expensive. I think there is a directory on this site, which someone else might be able to provide a link to.