That is a really small hoya to be 4 years old. I would check the roots out.

Is there a drainage hole in that pot.

The soil looks a bit dense, I would repot with a perlite, potting soil, and orchid bark mix. More perlite and orchid bark than potting soil though. Do that and your Pubicalyx will flourish! I have quite a few of them.

Make sure to get all the old soil off the roots and cut away any rotting ones.

Keep a close eye after repotting it, when going from a dense 100% potting soil mix to a much more airy mix like the one I suggested they often need more frequent watering. At least here in CO where we have no humidity.

The root ball is extremely dense, you can't push your finger into it or anything. It's like a rock! I assumed that was good because they like to be root bound, my mistake! And yeah the pot doesn't have holes.. it seemed ok so I didn't want to mess with it. I thought it wasn't growing because I always move in the spring so I was thibking it was just being stunted during its growth cycle. OK so new soil, new pot with holes and we'll see what happens! Thanks very much for your help everyone!

I have perlite but no orchid bark. Can you get that at a Canadian tire or should I check out specialty gardening stores? Thanks again

You can get it from ebay. A garden store might have it. But equal parts of soil and perlite work good.