Kristina, sorry for the late response.  I have found the advice given in the
26-week program offered for free on ast-ss.com to be very effective.  I can
only recommend eating more calories, and splitting off your cardio workouts
from your resistance training by at least 12 hours.  Maybe do your cardio on
alternate days.  Also, do intensive cardio, interval-training style.  I used
to use the recumbent bike, doing all-out as hard as I could for 1 minute,
low intensity for the next, repeat for 16 minutes.  Now I do the same thing
by running (sprint / jog).   In short, look at the musculature of the
sprinter vs the distance runner.  As a paleo eater and following this
regimen, I would bet large amounts of money that I would have to borrow from
my mother that you will lose fat and gain muscle.
Regards,
Lou Huis