I'm quite lefty and I make this mistake often, so often that early in my life my parents took me to the doc thinking I had some sort of issue. I believe my right brain hemisphere is quite more developed than the other and the information when travelling from one side to the other isn't so fluent as other people. No matter how much I talk and practice, it doesn't get much better, but I've learned how to better compensate that with either using my left brain or with character.

Don't see it as a defect. Make it a quality.

In the end, it's not much of an issue. It sucks to communicate sometimes and I know I will never have that politician way of talking, but you can say sorry and people are ok with that and with a bit of experience dealing with those situations, you actually get to be funny or show some character.

I have no trouble working on my expertise and do absolutely well in math and abstract stuff though. Even with languages I do just fine, can speak 3 languages fluently, some others a bit well. I bet you can relate as well to things you do much better above others, focus on them. Don't sweat it :-)