Alhamdulillah - I Returned to Islam After 8 Years, but I Grieve the Time I Lost

Assalamu alaikum dear brothers and sisters, I want to share my story. I grew up in a mostly Muslim country but in a family where only my grandmothers regularly prayed. Still, everyone believed in God and Islam in some way. At 15 I became very devoted - reading the Qur’an daily, praying, and trying to live for Allah. Those years were transformative: they gave me a clear identity, discipline, and helped me get into the top university. Before that I was lazy and struggled with studying; after embracing Islam I became much more focused and successful. Things changed when I moved from my village to the capital. I began mixing with different people, started drinking, and questioned religion. Over time I drifted away and went through phases of atheism, deism, then agnosticism. Even though I stayed successful in my career, I lost the inner peace and fulfillment I had while practicing Islam. Now I’m 26 and, by the grace of Allah, I’ve returned. I’m reading the Qur’an again daily and I deeply regret leaving the deen at 18. I wish I had kept growing in faith - I feel I missed years of spiritual and personal development. I want to make up for that lost time and strengthen my connection with Allah. I’d really appreciate your advice: how can I catch up and rebuild my spirituality, patience, discipline, and mental clarity? What books or practical steps would you recommend to increase my knowledge of Islam and revive the habits that gave me focus before? I used to have much better discipline and clarity when I was devoted; now I have a successful career but struggle with focus and self-discipline. Jazakum Allah khair for any suggestions or resources - books, lectures, daily routines, or practices that helped you grow in iman and character. May Allah guide us and accept our efforts. Amin.