日本語の習得はむりだと思います。

でも問題は：I couldn't understand what you are trying to say here. Is it something like "the problem is.... I live here, I work here, but my Japanese isn't good enough"? In that case, I would skip でも問題は and just say 今私は日本に〜. If you don't want to skip is and say something, I would say「しかし、今私は日本に住んでいて、日本の酪農場で働いていますけど〜」. If you are trying to say something like "I've been studying Japanese for two years, but THAT is the problem" (because you're now in Japan and working in Japan but you think your Japanese isn't good enough), I would say 日本語を二年間勉強しましたが、それが問題なのです.

I understand that Japanese is a tough language to learn, but you're doing really well! I corrected bits and pieces but I understood what you are trying to say just reading what you wrote! Hang in there! But let me know if I can help in any way :)

日本語の習得はむりだと思います。

You did well. All make sense for native Japanese speakers. I understand it can be hard for Japanese language learners to use the particles correctly. Most Japanese learners of English, including me, make mistakes in the use of English prepositions and articles too often. Don't worry about those errors.