Google has not yet updated my SERP listings to reflect my SSL
Even if you do everything suggested, it will take more time.
My site switched to https on 1 November (having ticked all those boxes), but only about 80% of https pages are indexed and listed today, and over 40% of the http version are still showing (i.e. there is some overlap).
Index Status in GSC was fixed in GSC a couple of days ago, but isn't updating in real time (so there is a discrepancy between the results of site:mysite.com and GSC Index Status).
Also, site:mysite.com doesn't show all the https versions unless I repeat the search to Include Similar Pages: clearly in some cases the results favour the historic version of the page.
In the results I have checked for key search terms, position seems generally unaffected (where the https version is showing, it is in roughly the same position the http version was), with the exception of my home page for main key term, which has moved from (http) #39 to (https) #22. However, there has been quite a bit of movement generally for that term, so I don't think the change to https accounts for it, although it is a possibility.
Note that .htaccess will not be available if your site is on an IIS server (in which case you'll need to set up equivalent redirects using IIS, which I don't know much about).