Am I losing my Iman?

Assalamu alaikum. I’m a Muslim and I still perform the five daily prayers. I grew up in a loving, religious home - my parents are very devout. For the last 4–5 years I lived in another city for university and went through a very rough patch: a breakup in the first semester, then drugs and heavy smoking. It’s been 7–8 months now since I stopped using drugs and nicotine completely. Six months ago my younger brother, who was 20, passed away, and that pulled me back into a deep depression. I tried to book therapy and already had in my head exactly what I’d tell the therapist, replaying years of my struggle. The appointment ended up canceled and I didn’t go again. After that episode I haven’t felt depressed the same way - I’m doing better and generally happy, living life. But inside I keep thinking that this life is the only one and that religious teachings are just a way to control people. Still, I pray five times a day because my family and community go to the masjid, and I feel proud to be there; I also make dua to Allah. I’ve never told anyone that I don’t believe. Recently I was talking with a friend and we ended up saying things like religions are cults. I read somewhere the idea that the moment you intend to leave Islam you are out of it, and that thought scares me - what if on the Day of Judgment I stand among those who associated partners with Allah? On the other hand, sometimes I truly feel there is no afterlife and that fear is just something ingrained from childhood. I also wonder if my intellect makes me see religion as a form of control. If I tried, I could write pages defending Islam - I used to always defend it in my mind - but deep down I feel I don’t have firm belief. Even my intentions to do things for Islam sometimes feel motivated by wanting my mother to be happy or to earn praise from the community. I’m sharing this because I’ve seen others go through similar doubts and wanted to speak honestly. Is this a phase that many people pass through? Jazakum Allah khair for any advice or duas.