My GP is actually very thorough. Besides, as a cancer patient I have to see my specialist once a year (more if necessary). Other than that — and barring a significant injury — I doctor myself. I’m in my 70s, and it seems to work for me.
But, I’m kind of like you: I weigh myself (I’m pretty fit for my age, and I’ve never had a weight problem); take my own P/R and oxygen saturation; check my own BP; and check my own temp.
I also started using less salt and added 16 oz water/day plus my coffee and/or milk.