If you recreated the same scenario with another male who is not balding, you would likely see a similar shape hairline from that angle, unless they have retained their juvenile hairline from childhood, which is rare in caucasian males.
I cannot say for certain it is mature but given your family history, the odds are in your favour. I'm afraid only time will tell if your hair will recede further but at this stage, in my view your hair looks good. I'm a lot older than you (41) and over the last 20 or so years, I have observed the hair of many of my friends and colleagues. What I have noticed is that true balding is normally aggressive from a young age. Lots of men lose their juvenile hairline early and then that is all, for many years, sometimes life. Those that went bald, suffered very fast recession, and or, rapid lose of density and hair quality across the top of their scalp. From what I can see, you do not appear to be in this position. However, I'm afraid that can change, for all of us, so just keep an eye your hair and if it genuinely starts to deteriorate, see a derm and consider treatments.
Regarding GP's, I personally found them to be no help at all when it comes to hair loss. No harm in speaking with your GP though if you are concerned.
What is your father's hairline like? The science says that the balding gene is 51/49 in favour of the Mother's genes, however, I have very rarely met a bald man who's Father was not bald also. Again, your family history is the strongest indicator you have.