Trying To See How Many People My Server Can Handle

So right now I'm hosting a server, but only my friends have access to the IP. That being said, there's no definite way I can test how many people at once my server can handle without lag/crashes. I know I can use canihostaminecraftserver.com, but I think my computer can push itself to host more people than it says can be the max. So can I please have a bunch of people log on to see what happens?

The IP is slytest.zapto.org

Just as saftey precautions, new players will not be able to build while there is the test. The redirect URL will be taken down after the test is over so noone can log on again until I give the real redirect URL to the public.