Karangan terpilih upsr

hey, i'll keep this relatively simple, im 16 and for this years goal i REALLY want to master my BM and Sejarah. for context, i was raised in the UK since i was 9 that lead to i guess, never became familiar with my cultures language
went through an extremely depressed state after UPSR from tingkatan 1-3 from the torment of people making fun of my lack of malay i never got much support from anyone to help me improve my BM, i never really took my exams seriously, my mind was just clouded with negative thoughts from the torments. from UPSR to tingkatan 3, i've only passed 3 BM exams out of my years and its frustrating and scary to think about how this can seriously screw me up in SPM now.. oh right, my first exam as tingkatan 4 came out, 31% on BM, 38% on sejarah, i really did try my best for sejarah i guess i was still unfamiliar of what even the questions were asking me?? i have always struggled with trying to understand what the question is trying to ask of me since its in malay. though recently, im starting to be able to UNDERSTAND concepts my sejarah textbook is telling me, the problem here is that as usual.. i can't fucking create the sentence out of my head in Malay but i CAN explain it in english. so i really want to know, how can i majorly improve my BM and my malay karangan within the span of 5-6 months? if you're going to tell me to read malay novel books, tell me what i need to do specifically to get it in my head please, luckily for me i do enjoy reading but its abit complicated for me to enjoy it when i need to translate constantly i can't even find my style of writing a karangan, do i need to be clever with understanding the concept of karangan or something? the pengenalan 1st, isi 2nd, kesimpulan 3rd?? i can't even create my own pengenalan either now that i think about it.. or even my own isi as to why a certain problem is bad, not without my translator.. i'm not even good at peribahasa or basic adjectives or even different types of kata's like kata majmuk/ kata tunggal or isi tersurat/isi tersirat like, where do i even begin my journey to really master my bm? theres so many basic things im missing and the thought of it is practically eating me alive

I am 16 this year, and I'm aware that SPM is next year for me. I have been studying in an international system (British, really) for as long as I can remember, since bapak aku kerja luar negara. I have never even done UPSR. I can converse well in Manglish and Bahasa Melayu, but I can't write a karangan without getting a B or C. Advice?
Edit: Currently I'm doing IGCSEs and GCSEs (the British equivalent) and I'm just worried about the circumstances surrounding my decision to take or not to take SPM next year. My parents say I don't have to if I'm not going to work for the government, because my exams this year are equivalent to SPM. I am aiming to use my GCSE results to enrol into UTP for chemical engineering, but I'm just scared I might get shot down like so many other occasions. I just want to "play it safe" and tread through this dilemma of a teenager carefully. Sorry for the lack of clarification.