How can I achieve my ambition in seeking religious knowledge to be like Sheikh Ibn Uthaymeen, and have I missed the boat in that, and what is the way to achieve this goal?

Congratulations to you for Allah's grace in enabling you to memorize the Quran and love knowledge, for "Allah will raise those who have believed among you and those who were given knowledge, by degrees." After mastering the concise texts, move on to studying the detailed books, continuously reading and noting down benefits. Let your ambition be high in seeking knowledge, and do not be content with little; seize your free time and energy. Take care in acquiring the books you need, and benefit from them as much as you can.