I suggest you seriously think about changing platforms
WordPress self hosted on a $7 a month host is probably a better choice economically for you. If you need tons of power then get a Amazon Cloud Server and go buckwild with WordPress like many of the top 1000 sites do.
Evaluate what you have
Go to the Plugin Repository and see if you can add any features to wp to supplement it to match your current needs.
Install it on a local computer
Get it looking nice and move it to a $10 a month server there are tons of hosts that can provide everything you need
Don't get me wrong Squarespace is Great... it gets people online quick
But when you need to expand your site and your current CMS is not cutting it then you have to take a long weekend and find a better solution.
Don't try to force an open CMS inside a Propitiatory CMS
just upgrade to something better and be done with it.