How to not hate people?

I've been practising meditation for many years now but I feel like instead of becoming more compassionate and understanding I hate people more than ever. I notice so much their selfishness and lack of awareness of those around them etc. In particular I cannot tolerate loud people who don't seem to care about the noise pollution they subject others to. Social media has made everything worse. Seeing people constantly staring at their phones and taking selfies for their instagram etc makes me cringe. Narcissism seems to have become normal behaviour. Much of the time when I'm at home I wear ear plugs so I cannot hear the children screaming their heads off, dogs barking, people laughing and shouting, cars with unnecessarily loud mufflers, doors banging etc etc. Nature sounds I find soothing but people sounds I absolutely hate and feel very triggered. Instead of practising metta I find myself wishing people would drop dead. So I know this is all not what Buddhism is about but it's how I feel and I feel conflicted about it. Is this common? Is there something I should do to try and change it. Metta practice feels useless to me. Its like pretending to feel kindness but underneath I feel nothing but hatred. Its just a glossing over.