To all of you out there who started later in life or came back after many years, the site below offers some interesting reflexions. It is by a piano teacher but in much of the discussion you could just substitute the word "trumpet" for piano. I found it helpful in that it formulates many things I sensed but could not quite put into words as plainly as the author does.
Hope others will find it helpful too.
Musical Fossils - Freeing the Adult Musical Student