@womble7 The problem with your calculation is you aspire for an upper middle class post retired lifestyle, and want to build a corpus before age 45.
Why 45? that is too young to retire. You would be in the prime of your experience, maturity and would be still relatively healthy. You should be focusing on increasing your income at that age. Retirement is okay after 55 or so. You will get fully bored once retired.
The only happily retired and not bored people I have seen are 70 plus. Happy to wake up, chill the whole day, and sleep at night. All retirees younger than that seem bored and frustrated and turn into typical judgemental whatsapp uncles/ society president/ shaadiwala fupaa ji types. Don't do that.
Dude, 27 is too young to focus on 60 years into the future. Live the best life you can without spending or splurging too much, and invest the surplus wisely. The point of FIRE is to live well, not live miserably.