I’m hearing 3 things here...
You have a lot of planned things to do on your plate
You get a non trivial amount of unplanned work
1 and 2 are causing you to miss deadlines
You need to put 1 and 2 on a view that you and you’reyour manager can see so that you both can see what’s on deck and take appropriate actions (e.g. change deadline, prioritize urgent things, etc).
A 3 column Trello board should be a good start. To-do, doing and Done. You and your manager add cards (tasks) to the To-Do column, ordered by descending importance. Your manager arranges the cards according to priority. You pull the top card on the to-do column and work on it, then move it to done when you’ve finished the task, then pull the top card from the To-do column...repeat. Tweak as needed.
That will at least allow you and your manager to see the same things and see patterns in your workload that can be / should be addressed ( e.g. you’ve fixed X 10 times for the same thing...maybe we should make code changes to handle that).