Struggling with doubts even though I want to believe - seeking guidance, please

Assalamu alaikum, I hope this is the right place to ask. I'm writing because I genuinely want help and guidance. I grew up in a very atheist and somewhat toxic household where religion was often mocked or treated like a joke. Because of that, I never had a spiritual foundation while growing up. About three years ago I met my partner, who is Muslim. Over time he patiently answered my questions about Islam and never pressured me. At first I was hesitant and didn’t even want to hear about it because I was afraid of being “changed.” Around six months ago I started to develop a real interest on my own. I began watching lectures, learning more, and I’ve started reading the Qur’an. For the most part, Islam makes deep logical and emotional sense to me. I want to believe. I want to take the shahada. But every time I get close, something in my mind suddenly says: “This can’t be true.” I don’t understand why this happens, especially because believing actually feels like the most logical explanation to me. One doubt I can’t seem to shake is about human height and lifespans across history. From what I’ve read, some early peoples and prophets are described as taller and living longer, then later populations seem shorter (like Ötzi’s time), and now in modern times people are getting taller again. I’m struggling to make sense of why humanity would go from taller to shorter and then taller again. This question keeps coming back to me, and I would really appreciate any explanations or perspectives, both Islamic and scientific. Something else happened recently that confused and scared me. Last week, while reflecting deeply, it suddenly felt very clear in my heart that Islam is the truth. But immediately after, I heard a thought in my head saying, “This is not true. You’re going the wrong way.” What scared me was that it didn’t feel like a normal passing thought - it felt very loud and distinct, and I could almost “feel” where it came from in my brain. That experience left me shaken. Now I don’t know what to think. Am I overthinking? Is this anxiety? Is it whispered by Shaytan? Or am I still affected by how I was raised? To summarize: I want to believe and to take the shahada. Islam feels right to me logically and emotionally. But something keeps holding me back and I don’t know how to move past it. If anyone has gone through something similar, or has advice, explanations, or even just reassurance, I would really appreciate it. Jazakum Allah khair for reading.