Google is tough on security so you need to follow the recommended security steps using:
Account Recovery
Reviewing Recent Sign in Activity
Confirming what apps and devices are using your account
Reviewing 2 Step Verification
If you take the two minute security check steps your additional 2 Gigabytes will be added immediately or by the end of February to your Google Drive Storage. You can continue to use the Security Checkup after February 17, 2016 to check your Gmail security.