you got 3 blank spots you got room. don't be to concerned about the total amprage of the breakers compared to the main breaker, there is a formulae for how many breakers you need and then how much power would be drawn at any given time. if you have electric heat it is even worse.

you got two choices here, well 3 realy, pull a home owners permit and run two circuts your self if you are confadent in doing it as it can involve framing, drywall, ect skills in adition to the electrical.

option two, hire an electrition to run two 15 amp circuts, probably would cost 2 to 300.00 depending on how hard the run is.

and option 3, upgrade the box to a 100, or 125 or 200 amp box. or the most convoluted way would be to add a new pannel and power your old one as a sub pannel. this is the messiest way to go, puts pannels in two parts of your house, basicly a bandaid solution to a problem, but havign said that I installed a sub pannel instead of upgrading my main pannel because I would have had to do a bunch of other stuff to bring my mast and meter up to code which wasn't in my budgit. it would have taken a 1000.00 buck job to a 3 to 4K job. and in my case we are planning on doing renos in the future so at that time I will upgrade the service and main box.

If you use an electrition, call around get several quotes, asl about peermits as they are needed for adding circuts. make sure you see the permit and get a copy for your records.

Steve