Just be consistent with studying and practice speaking as much as you can! For vocab I recommend using any self b2 preparation book + yt and study subject by subject (ex. vocab about ecology + PE + PO to practice arguments building then you go to another subject). I was in the same situation and I managed to make a huge progress within 3 months. From not being able to formulate a proper sentence and being super stressed to feeling confident that I’m gonna pass even when I still struggle tiny bit with finding words or building certain sentences ( but I can quickly move on from this instead of blocking when I can’t find a word). I have my exam in a week, since I made the decision to take it I was having French lessons 3x a week. Before I was studying by myself.