Good morning a51ts4 san ! ohayoo! It's fine if you use a few Japanese words in your posts. The medium language is English, however, and so if a post doesn't have too much Japanese, and often enough (not every single time/word) the English translation, it's no problem. In the area where Japanese is being learned, or the fora which is for writing in Japanese, of course, in Japanese is 100% OK. Please do check those out.
I would suggest that you learn the katakana, and especially the hiragana, right along with you oral communication. Even trying to memorize the kanji (Chinese characters) for some vocabulary is recommend--the purpose is to increase the accuracy of sight reading rather than simply phonetic reading.
Japanese kana is read phonetically, but reading it that way slows the reader down. If a person can recognize, say, わからなかった (wakaranakatta) right of the bat via visual contact, it will be much faster than having to go through each character...wa, ka, ra, na, ka, tta. Do your best !! and keep up the good work.