I have worked as a software consultant for 4 years at companies like Amazon, Hitachi, etc.
There's a lot of variance between the expectations of each level between each company, but this is the general guideline I follow.
Hooe this helps!
So, I can build features independently and I believe I am pretty good at breaking down tasks and managing my time.
But I have never worked under an actual senior software engineer who could mentor me, so I am a little hesitant and less confident about where I stand as an engineer.
Am I a junior/mid/senior is the doubt and also a fear that will I be able to take on the responsibilities given, if I get into a senior position.
Based on your rough description, it seems like the ballpark is midlevel. So I'd set that as your target baseline. You should feel free to apply for senior though (if those are the only open roles) and see what happens: usually, big tech companies give you a +/- 1 level range for roles.
I'm 90% sure you should apply for mid-level roles. Here's what that means alongside some additional context:
Here's another great discussion around what level to pursue: "When should I down level myself on purpose at a new company?"
Best of luck with your interviews!