How do I measure actual fluency progress for the CAPLE exam?

I’m currently studying for the official European Portuguese proficiency exam and feeling a bit lost. Apps like Duolingo aren't giving me the measurable progress I need for the B2 level. Does anyone have a systematic way to track improvement in complex verb conjugations and formal writing? I need to know if I'm actually getting closer to the CEFR standards or if I'm just wasting time on ineffective exercises.