Eyebrow growth?

I've been growing my eyebrows out for about 6 months now (no plucking or waxing) and it seems like they're making no progress. The right one has a single line of new hair growing with bald patches in between while the left has only 3-4 new hairs. My mom started waxing my eyebrows when I was about 9, and I continued for years (I'm 20 now) so they've always been sort of thin. I hate the way they look now since they're so patchy, and was told by a beautician that if they haven't completely grown back in 6 months they won't come back? I use castor oil every night as well. To get to the point, should I just wax them/have them threaded to a shape that looks more neat or just continue letting them grow?