DDH - please hang in there. I think the old saying of patience is a virtue comes to mind.
About the terrain where you live - hills 24/7 - believe me there is a big silver lining to this. I just got back into riding about 6 weeks ago after a 6+ year absence. Where I live we have lots of mountains and hills. So while at times you may feel slow here's the caveat. I have made it a point to absolutely love hill climbing and do it every ride - in those 6 weeks guess what?
I am easily stronger than I was after 6 months of riding way back when I used to live in florida. The hill climbing may make you feel slow but it will build your ability faster IMO, than just cruising the flats.
I find much of what makes climbing doable is all in your head - pace yourself, relax, enjoy the scenery, think of all the calories you are burning. You'll get there
About cadence - I like what Roadraven said. You don't need to be cranking 100 rpm to be effective. Every body is built differently and yours will have unique needs. It may be you perform better at a lower cadence - which is perfectly fine. Granted you don't want to be pushing an enormous gear at say 35 rpm.
If you are serious about turning the pedals faster than try spinning in an easy gear. Even better, do so on a downhill and get your cadence way way up while trying to not bounce in your seat. Finally, if you have clipless pedals, do some short, easy stints with just one leg - that will improve your technique.