Hi Scarejo - and welcome!
I'm much like you, except I'm Level 72.
Still finding new locations! Like the Boston Mayor Bunker. Never seen it before.
Cleaned it out just last night.
Walk around! Here are two good techniques:
From Diamond City, walk directly south.
Plenty of little places, off the beaten path, you've probably never encountered...
And (more advanced) - starting at Sanctuary, go back and explore Vault 111 thoroughly.
Claim the Cryolator.
Then, follow the border at the extreme edge of the map and travel either east or south - your choice.
Point is, do a 'lap' of the extreme border region, either clockwise or counter-clockwise.
There has got to be like 100 hours of stuff to explore and just walk around.
Look for things on your PipBoy map!
You know how they are a different colour if not yet 'discovered'...
Plenty still to do and see. Especially down in the Glowing Sea - I spent DAYS just walking around investigating stuff down there!
As a further resource, refer to the Wiki.
It will list every possible Side Quest and Miscellaneous Quest. Make certain you've done them all.
And there's also a map there, showing every marked location on the 'world'.
Though there are plenty of locations that are not mapped...
Also - have you built a Bobblehead Stand, and filled it with every possible Bobblehead?
Build one and see how many you're missing...
The Wiki is an excellent resource to help you locate and claim any Bobbleheads you've so far overlooked.
Good luck.