I guess I am suck at multi - tasking

Doing specific things at the same time works wonders and it will give us more opportunity to do more tasks later on. But this "multi-tasking" thing is not for everyone. Others can do only one given work at one time. I think as a part of a habit, it grows and develops. While for others, they are just gifted and can do it "without a sweat" and rely with it in doing multiple works at the same time. If you are into this "multi-tasking" thing and want to improve and do more, my advice is do it first with non-critical works since a mess-up might be the end result. Nobody wants to be in a messy situation just like you said. Train...it will make you better and ease with this multi-tasking if you want to continue or if you still have difficulty are so many tries, I guess you need to understand that it is not your thing and just go back to the normal habitual things how you can manage your pending works done and then do it in chronological order again and stay away with "multi-tasking"... My piece of thought...

Making multi-tasking a habit will result in a bother when you don't have nothing to do. In that case, it is already a problem but somehow a good thing in some sort.

Multitasking is probably good for your brain, but I wouldn't be dependent on it at all. I think, overall, people are much more efficient when they focus on one task at once, and that multitasking is better for negligible tasks, such as doing laundry while talking on the phone.