Not bad, however there are a few things that would need polishing.
Waves sometimes are too hard, without visible empty space.
I'm not sure if ammo packs are random, but I couldn't find any a few times.
Also rockets could be more intelligent and less spammy.
It turned out that the best strategy is to shoot everything you have almost instantly, with small breaks = 50% boss hp, a few seconds after start.
Keep up the good work
Ps I couldn't make it to the end :(