Most of the compute cost ($2400) goes to an m4.xlarge and an m5.2xlarge. That could be reduced by using reserved instances - but there's other gotchas there if you're likely to change that anytime soon. Google cloud is much nicer in this regard with the auto discounts for continuous usage.
The provisioned IO for EBS $2500 makes me sick, but may be necessary to get adequate performance.
Honestly you could move everything onto two dedicated servers (one as a hot backup) and cut this down to $1000/month and get better performance. But that's the AWS tax.
I use AWS all the time for work, but I would never build my own business on it.