But, yes, BACK TO POLISH FINALLY
Your Polish is truly horrible (I know your broken Polish) and I can say with all confidence that it is no match for the English of many Polish speakers here on this forum and outside of it, so I would suggest you do no limit your shortcomings to just inability to count - don't be funny.
You are partially bit not quite right about problems Polish speakers face with English.Tenses are a problem but have in most cases have clearly defined rules as in "I do" - statement about doing something on regular basis in contrast to "I am doing" - statement about doing something at this very moment, this is not difficult to learn and most Polish know the difference. While less clear distinction between "I would' and "I would have" or "I have" and "I have had" there comes some difficulty. Articles are the least difficult with definite article like "the" denoting the specific subject matter (a noun) and the indefinite one "a" being the more general one, while "an" (another indefinite article) occurs before a bowel, this is all not difficult. Prepositions are the ones most difficult as these have to be learned mostly by experience, there is no clear rule to them. I would also add to the list the irregularity of English spelling as a category in English gramma that poses difficulty for Polish speakers.