If you have a less than ideal monitoring environment (well-placed full-range speakers + acoustical treatments) gauging the low end can be next to impossible. Spectral analyzers such as Voxengo
SPAN are your friend. They'll let you visualize your low frequencies, and if you import some of your favorite commercial recordings you can analyze them for comparison.
I'd suggest "Road Home" by Jordan Rudess as a reference. It's a homage to classic synth hits of the 70's (e.g. Tarkus) but being from this century it's mastered to modern standards. By that I don't mean squashed to death, but loud and full-range.
Your stuff is definitely in that vein. Love it.