CentOS7 systemctl calling ExecStop on reboot after the procceses are already killed

I have a systemd script which is as follows:

 [Unit]
 Description=My sites
 Before=shutdown.target reboot.target halt.target

 [Service]
 Type=oneshot
 ExecStart=/bin/bash -c '/etc/xxx/mySites start'
 ExecStop=/bin/bash -c '/etc/xxx/mySites stop'
 KillMode=none
 SendSIGKILL=no
 TimeoutStopUSec=5min
 TimeoutSec=5min
 TimeoutStopSec=5min


 [Install]
 WantedBy=multi-user.target

Now…if I try to execute sudo systemctl start mySites.service it seems the service is run and all my stuff is started correctly. If I do a stop it works too. Then, at OS boot, it also starts correct. The problem is on the OS shutdown. I am rebooting it and it seems like if the ExecStop WAS called too…but too late… I see in the logs that my processes all received a kill as I can see in my logs:

 signal 15, SIGTERM, received from process 1 userId 0
 si_code: 0, SI_USER, signal from kill(2), sigsend(2), raise(3C) or abort(3C)
 si_signo 15  si_errno 0

So..ExecStop seems to be being called too late because someone already killed the processes I originally started. Yet, I am already setting Before=shutdown.target reboot.target halt.target.

I think the problem might be that my ExecStop may take longer than the default timeout, and hence systemd ends up sending SIGTERM. Now… I have set KillMode=none, SendSIKKILL=no and even all the possible timeouts to 5 minutes to TimeoutStopUSec, TimeoutSec and TimeoutStopSec (for sure my ExecStop takes less than 5 minutes).

Still no luck.

Any idea how can I fix this? I am running CentOS 7.

Thanks in advance,