I think you may have misconceptions about Catholic doctrine. For example, below (first link) is an article titled "Mary, Gate of Heaven," by a Catholic cardinal. Note that he indicates that, since Mary gave birth to Jesus, she opened the door to to "the great achievement...of our Lord Jesus Christ, who came to save the world by dying on the cross for it."
In short, Mary is the door to heaven in the sense that she was instrumental in bringing Jesus into the world, not that she's the way to salvation, which is only through Jesus. As another example, the second link below is an article titled "Is Jesus the Only Way to Salvation?" by a Catholic writer. Note that he also states that the only way to eternal salvation is through the "Good Shepherd that lays down his life for his sheep."
https://www.cardinaljohnhenrynewman.com/mary-gate-of-heaven-cardinal-newman/
https://catholicexchange.com/jesus-way-salvation/
I would be interested in the "bunch of other things" you refer to that cause you to believe that Catholics don't believe that Jesus is the only way to heaven - preferably from Catholic sources. (There's lots of information floating around about what other religions believe, but often it consists of misconceptions, uninformed opinions, etc.)