Are all sins forgivable?

I am in desperate need of advising. Recently, I have been connecting more with my religion and it’s never felt better. But something has come to my attention that is causing me a serious amount of distress. Astrology is something that is becoming so popular all over the world. Some believe it while others just look it up for fun. I never had a belief in it but like others, I thought it was fun but wasn’t really all about it as others were. One time, I saw the criticizing of Astrology from an Islamic perspective a while ago, and by thought that surely it doesn’t mean anything if you don’t actually take it seriously, right? Then a long time later, I found out that Astrology is Shirk by one article, and I was completely taken aback and treaded such areas carefully. I thought that surely there was an misunderstanding, because I don’t think I knew what that word actually meant—I thought it meant the active belief of the existence of more than one God, which I have obviously never believed. Still, I remained cautious. Then, after a short while, many girls in my class were having a discussion about their zodiac signs. Many of them had a similar one so they had this long and elaborate discussion. I was very weary, but utterly lost because these girls were not only Muslim, but they were born and raised in a Muslim country. They only felt the need to clarify that they didn’t believe in Palm-reading and had only done it once for fun. This is also common. I was so confused at this point and thought to myself, if these very much practicing Muslim girls are saying these things, then surely I am mistaken, and it was not Shirk. I laughed when they made jokes in the conversation and they asked me for mine but I wasn’t really contributing much. Still, I remained cautious of the topic and refused to approach it. My brother also told me it was Shirk. After a while, I heard of many other examples of Shirk I didn’t know about, like putting your wedding ring on your ring finger. I am now realizing how many incidents there have been that could’ve been Shirk in my life, which I never thought to be Shrik, especially because I was raised in a western country. I am absolutely terrified at the moment. I have never believed that there was another god than Allah and inshallah never will. But I cannot get this out of my brain. I can also not get out of my brain how many people believe this is unforgivable. I know we should never limit the mercy of Allah, but do we know that this can be forgiven?