I don't think you want to count your house, since you don't want to liquidate it. But, you can do it if you are willing to take on a little more risk!
Current assets: $400,000. But only $200,000 of that is going to earn anywhere near enough to provide you with income. Maybe make that $300,000 by moving more to the Vanguard from the checking account? $100,000 is 3 years of living expenses, and after the SS, it is more like 6 years. I don't think you'd need more than that in "cash" that is not earning a return.
So, I'm assuming that you, and your child, when you retire at the end of this year will need $35,000 a year to survive until you are 60, at which point you'll get additional income. That's 4 years and $140,000.
SS income in that time: $18,000 x3 years= $54,000
4% SWR on the $300,000 in Vanguard= $12,000 x 4 years=$48,000
Guitar shop sales: $6,000 x 4= $24,000
2% interest on deposits $2,000 x 4= $8,000
Total: $134,00 So, you would probably need to cut $1,500 in annual expenses, invest $37,500 more in the Vanguard, sell an asset, or work enough to bring in $1,500 a year. If the assets aren't appreciating and you view them as financial rather than sentimental, I would sell one and add that to the Vanguard. That would bring the number up to $14,000 from the market, which when added to the $18,000 SS would be $32,000 a year and it sounds like you could make that work if necessary. Or, as a public school teacher with a kid still in school, I would think you could easily substitute teach or tutor enough to bring in that much annually?
Then from 60 on you have $35,000 a year needs- $20,000 a year fixed income. So, you need assets paying out $15,000 a year. I'm thinking we shouldn't count on the guitar shop at that point, to be safe. That would be $375,000 invested. Add an additional $25,000 from the sale of an asset or additional income over the past 4 years in the Vanguard (or maybe more?).
Now let's try:
4% SWR on $325,000 in Vanguard: $13,000
2% interest on $100,000 in checking: $2,000
Your backup/ safety nets: The guitar shop may keep paying for a long time, you could substitute teach, you could probably reduce your expenses to $30,000 a year and need only $250,000 in the Vanguard to kick off $10,000, presumably at 65 or 67 you can take your own social security (right?), liquidate the $50,000 in assets, or sell the house/ reverse mortgage.