How to find my permissions in a SQL Server database?

I think the easiest way would be:

SELECT * FROM fn_my_permissions(NULL, 'SERVER');  
GO 

I tried it in SQL Server 2008.

Ref: https://docs.microsoft.com/en-us/sql/relational-databases/system-functions/sys-fn-my-permissions-transact-sql

If you're looking for what you might be missing as well as what you have, here's a useful way to find it:

SELECT all_permissions.permission_name, p.name
FROM (
    SELECT DISTINCT permission_name
    FROM sys.database_permissions
) all_permissions
LEFT JOIN (
    SELECT b.name, a.permission_name
    FROM sys.database_permissions a
    JOIN sys.database_principals b on a.grantee_principal_id = b.principal_id 
    WHERE b.name  = '{YOUR_NAME_OR_GROUP_NAME_HERE}'
) p ON p.permission_name = all_permissions.permission_name