No experience with child psychology other than having a nearly eight month old DD but just wanted to say that what you've written sounds completely normal from my perspective.
I can't remember how old she was when she started, but my DD always liked scratching surfaces and like you, was a bit worried at first until I googled and asked around... Most babies do it apparently as a way of feeling new materials.. DD doesn't do it so much now she has much more dexterity in her fingers but still loves exploring different textures and objects. One of her favourite things is to fiddle with zips, buttons and poppers! Oh, and labels, she loves labels!
She also went through a period of at least a month where she stopped making sounds which again worried me but it was when she was learning to roll over which is apparently totally normal... There's so much for babies to learn so it's not surprising they concentrate on one thing at a time. When she started making sounds again, it wasn't her previous cooing but a weird cat-strangled screeching sound! I can't remember exactly what it was like but I think I recall it sounded like some of the dinosaurs from Jurassic Park!
She then went through a phase of extended As and is now onto mumumum and Dadadadad so her vocal skills are developing pretty normally!
She also went through a phase of seeking quite serious when we were out and about (which got commented on by HVs
) and would only really smile at home but now loves going to groups and seeing friends.. It's really sweet actually.. She'll give me a huge grin when we get somewhere as if to thank me for taking her there!
Anyway, babies do seem to go through these weird phases (DD's is to now use me as a climbing frame and eat my face) but I think in 99% of cases it's just a normal part of their development.
Not meaning to dismiss your concerns but it sounds totally normal from my own perspective.
And I can empathise with the anxiety.. My own current worry is that DD's cumulative whacking of her head (she's recently started crawling and pulling herself up but is pretty clumsy!) is going to cause some damage... But the important thing is to try and rationalise it. And I also understand about obsessing over one thing because that is the only thing you have to think about, I'm the same.
Hope your doctor's appt went okay 