There are only a few places for the CO2 to go:
1. Dissolve into the water -- a good thing.
2. Collect at the top of the reactor -- would become obvious at some point.
3. CO2 leaking -- sounds quite likely in your case.
I do not think a slight angle in the reactor would hurt it. I would first try to eliminate the possibility of leaks.
Also, what type of tubing do you use from your drop counter to the reactor to carry the CO2?