Grammar VS Fluency

I've been learning English grammar since I was young. I still remember back then at primary school when teachers taught us a lot of grammar, grammar and grammar. It sucked! To be honest, I didn't understand anything that time! English competency was totally out of reach. I did have a long list of vocabulary but clueless on how to put everything together, particularly on how to use different verbs for different tenses. Teachers told us to remember verbs in the past tense, past participle, past continuous etc.

“When you speak about things in the past use past tense. Use present continuous for this, present perfect for that, past perfect for this...”

I yawned in the classroom. In fact, I almost gave up on learning English. They also gave us a long list of verbs to be memorised. Still, my English didn't improve much. All the lessons they gave were wasted. All the grammar, reading and writing lessons I used to have were useless. I didn’t know what I read, how to write and what I had written. Having English exams at that time was like a gambling game. I was guessing all the time, because I didn't know grammar, let alone how to use English accurately. This was a huge mistake in conducting a language class, where students were given tonnes of lessons on grammar prior to learning to write and speak. Understandably, English isn't Mathematics, where you can use formulas to solve problems. Learning grammar before speaking and writing is completely rubbish! It's like forcing our brain to retain a lot of information for a very long time, and when the time comes for us to speak and write, all the rules must be applied accurately. Silly! Who says this technique is effective? I feel so sorry that I had wasted more than ten years at schools learning English the wrong way. I believe that it’s not the grammar that makes an English speaker great, but fluency. Even so, how do we achieve fluency anyway?