yes, according to the teachings of tibetan NKT or other mahayana buddhisms. Of course it is bad karma as those are sentient beings. generating bad karma is extremely easy. we all do it. so don’t feel bad about it. i do kill mosquitoes myself sometimes.
but try to change and place them ouside.
if you want to begin practicing kadampa or similar traditions, do vajrasatva purifications to change your conduct little by little.
it’s probably not a lot of bad karma as insects seem not as sensitive and conscious as mammals, but yes it is unskillful conduct to kill them specially out of unfounded fear.
and yes, you are not beyond redemption. no one is. you are a valuable being tha can reach enlightenment.