I know my personal experiences are colored differently because I’ve been working with and under coders that happen to be women for decades.
I’m sorry your environment delayed you from entering a field you have an affinity for. That said, while I’ve been coding for over 20 years there are still times when “I” feel like an imposter simply because I know I could do more/better at times.
I have no doubt there are road blocks out there, but there are also quite a few advantages as the demand for qualified computer professionals that are not straight White/Asian males is especially high right now, though proving competence can be daunting at times.
One of the unspoken reasons why white males get hired is that they are easy to fire if they can’t do the job, but if they are other than that you had better have your absolute proof lined up or be exposed to unfair lawsuits and damage to your reputation. Many of the women applying to work in computer science now are doing it not out of a love/affinity but simply because it is well paying. Men do it too, but, like I said, they are far easier to let go.
As to 15% at “top” tech firms, whatever “top” means, it really does not matter. What matters is that those people who are qualified be allowed a shot. If that 15% reflects the talent pool, there is no problem. If it does not, then its an untapped resource that hopefully will be accessed.
Admiral Grace Hopper was an amazing woman/teacher/leader and I hope the courses named after her do justice to her legacy. Her words inspired me back in college and I wish you good fortune on your journey.