I think your problem may be that you're "too diversified" in your skillset. It is not a problem in itself, but if you stuck to one aspect of your skillset and mastered that, then this particular specialty can pay higher than a person that can do a bit of everything "decently". (If that makes sense) It can also go the other way, as some shops are looking for employees that can do anything, like yourself. But, in my experience, those shops generally are smaller and pay less.
It also all depends on what type of shop you're working for, what they're looking for out of an employee. I "can" do "everything" here at the shop and often assist in every department whenever necessary, but my primary job here is the lead designer, and my pay is based on that "position", and with also the knowledge that I can step in and assist wherever necessary. We have "department leads" in each department who manage the others and direct them to which projects they work on based on their skillsets, and those leads make a decent deal more than you're talking about. Everyone here works in a specific department/function 95%+ of the time, so their pay is based on their skills in that dept/area.
The other problem I see in our industry is keeping up with competitive wages, we have had new employees come in making the same as tenured employees due to the rising costs we are facing and competition for employees. We are in a large city and there are places/factories everywhere who are hiring on for around $20/hr+, so getting anyone in the door for less than that is very hard to do.
It can also have a lot do do with your location in this case, as larger cities definitely pay more, but then you have to deal with all the other things that go along with that like commuting, increased living expenses, etc. So, the pay may be higher, but everything else there is percentage wise higher, so there are still no gains made after expenses.
Points to ponder - How large is your current employer? Is your shop actually really busy, or does the workflow kind of ebb and flow? What is the cost of living there compared to other areas?
I also hear of shops in Florida that have a very cost of living in the area that pay less than rural shops, so you never know...
FWIW, I would say around $30 or more would be fair for your skillset, but a lot of that you can't just state on the internet, your employer has to see the value they get out of you on the job.