You can access your RPi from anywhere around the world if you use this:
ngrok
Quick steps to get you started:
(adapted from instructables.com/id/Raspberry-Pi-online-SSH-easy-way/?ALLSTEPS)
sudo wget https://dl.ngrok.com/ngrok_2.0.19_linux_arm.zip
and then unzip it using:
unzip ngrok_2.0.19_linux_arm.zip
at ngrok website go to:
dashboard.ngrok.com/user/login
and then click sign up to get an authtoken key. this token is necessary if you want your own custom domain doing an online SSH
after you manage to login you will get an authtoken key which a combination of a lot character.
You need to embed this token to your raspberry pi using:
./ngrok yourauthtoken
Now you can make your raspberry pi system to be controlled online using
./ngrok tcp 22
Using putty, enter the following IP address and port no:

By now you should be good to go!