Comprehensible Input alone often fails to build sufficient explicit knowledge of grammar, especially for adults over 50. Combining CI with structured grammar instruction and practice is more effective. Your current tutor can help you fill those gaps.
The frustration you're experiencing is common among learners who rely heavily on pure comprehensible input. While CI is excellent for developing intuition and listening fluency, it does not automatically lead to conscious understanding of grammatical patterns, particularly for older learners whose cognitive processing preferences may lean more toward explicit learning. The Dynamical System Theory you mentioned focuses on self-organization, but language structure often requires explicit scaffolding.
Your real-world comprehension struggles likely stem from two factors: (1) CI materials tend to be simplified and highly repetitive, which doesn't prepare you for the speed, vocabulary range, and grammatical complexity of natural speech, and (2) without explicit instruction, you may not have noticed important patterns like verb conjugations, subjunctive mood, or pronoun usage. The tutor is exposing these gaps, which is actually a positive step.
A practical approach going forward: use your tutor sessions to systematically study the grammar structures that keep tripping you up (verb tenses, sentence word order, cases if applicable). Between sessions, continue limited CI (podcasts, TV shows with subtitles) but focus on noticing the patterns you just learned. Keep a journal of sentences you hear in the real world and analyze them with your tutor. Supplement with spaced repetition flashcards for key grammar points and high-frequency irregular forms. Be patient with yourself: learning a language at 65 is a different cognitive process than at 25, and progress will not be linear.
Tradeoff: pure CI is low-stress but slow for grammar acquisition; explicit grammar is faster but can feel tedious. A balanced mix (70% CI, 30% focused study) works best for most adults. You have not wasted time - the CI built valuable listening stamina and vocabulary. Now you need to build the structural framework on top of that foundation.