You are doing great! I also had some moments where I realised that he had so many needs, what if I got sick and suddenly there was no one to look after him etc. All very natural.
You taught him to point too, so you are obviously able to pass on some skills, which is brilliant. Some days I don't see any change at all in my son, for a while he seemed to drop everything he knew before. It's all stops and starts.
I'm no expert, but once he is asking for things by name, just keep it up a lot. And then introduce something like action verbs, the obvious ones like jump, eat, walk, drink. You can do it in lots of ways, from books, or just saying it a lot (or however much your child can handle, with mine, he can't handle a lot of talking to him at all) while doing it. Also things like - 'up' 'down' and body parts 'where's your nose' - took me AGES - as my son didn't understand very much at all.
As an example he screamed at me every time I even demonstrated 'touch head' and then screamed even more loudly when I moved him hand to 'touch head' on himself. I didn't want to overload him to tried to do this daily but not very often.
So there were times I just felt despondent, is this helping him etc, how long does it take, my son was basically totally behind developmentally with so many things. And then, as if by magic, suddenly, he started doing all of the above and I can't stop him coming up to me while he shows me where his nose is, jumping, eating etc.
Combining even two words also seems to hurt my sons head, he'd much rather repeat a phrase. In fact, interaction was non existant. But gradually, by often adding a word to his, or by using really simple language, we can do 'Look bird' or 'See dog' or on a good day 'want cookie'. It's all at your child's pace. Anything that you can do to get your child's shared attention, whether it's exagerated 'Look... tree' or jumping up and down with them saying 'jump'.
My son also hits his head, on and off, usually when stressed and does it a lot. I tell him no hitting, move his hands down and do whatever it is that calms him down, often grabbing him for a big cuddle. A lot is trial and error. What works for you might be different.
You don't have a diagnosis yet do you? It's hard to say what would help most - as there is so much discussion about what is best. A lot of people say ABA works very well, but that is intensive and requires supervision - an educationa psychologist may advise about that. Speech and language therapy could help, depending on who you got - mine just said use picture exchange but didn't actually assess my son at all. Occupational therapy helps with sensory difficulties.
I'd say it's helpful just to get started anyway. Write down under 'communication - expressing and understanding' - 'social' - 'physical' and 'behaviour' - what you feel your child's strengths and weaknesses are. Then look at what you think are the most important - usually communication and any problem behaviour - then get as much information as you can and get some private assessments with recommendations if you can. Read up about ABA and see if it is right for you.
Good luck! Don't be too worried about the future, who knows what it will be, but your child has a very proactive and loving parent it seems in you, so they will be getting a real head start whatever they are capable or not capable for growing into. 