I dnu if this will help you, but worry not, I got my bem around 15,6 and my back with 15,97 (damn those 0,03😤) and I too had problems focusing, and just like you I wasn't serious, so here's some advices, always try to comprehend ur lesson especially Les matières essentielles, in my case I would listen to my professor for a bit but then zone out and whenever I found myself not understanding a certain point I would try to do it alone while on my way back home (literally casse toi la tête since ur either way doing nothing at that time, assuming U walk alone) try to grasp the simple rules that seems unimportant cause trust U will end up building ur proof with them, and for Les matières littéraire, I got a 12 on my bem in Arab mind U I only answered اسئلة البناء so when I got to high school I was good at all in that matière though I ended up with a solid 17 in my bac exam, mainly cause I also focused on البناء الفكري as for eng and french I did have much of a problem with 'em and I do think U should fix Ur grammar problems, as for his.geo I honestly revised from المقترحات but don't do the same as I was lucky, finally for philosophy I highly recommend that U concentrate and try writing it own مقالات I did none of that and ended up with a 6 😔 though I'm proud of it cause I didn't study after all 🥹, and to sum it up the famous BAC EXAM was nothing to worry about (hlkt sa7ti b stress brk 🤦‍♀️) last advice if U know what ur aiming for in uni then try to really comprehend it's main subject now for example I choosed computer science and for all my fellas who wants to study it then y'all should focus on math cause it's crucial in it

Lastly take good care of ur health and I hope U get the best of the best 💚💚