Fun and sexy, far from finished.

I would say the game needs to recalibrated so that;

1. The enemies can actually be killed via melee weapons or some options that acknowledges a lack of bullets.
2. Enemies have lower health bars.
3. Faster firing rate (not strictly reload time).

Either way, the main issue seems to be that you can barely complete any one wave without being overwhelmed, and that's not a sign of difficulty, just a lack of balancing.