hon, i don't think you did anything wrong. it's just that way with combo-classes.
now if you had made magick your preference, with combat second, you would be experiencing the same thing in reverse.
take heart tho. you don't say what level you are, but the first 5 levels go really slow, esp for a dual class. you will find your way tho, just keep working at it. the way i understand it, your favored skills add +.50 to your levels while your major skills add +.25.
another thing to keep in mind, that really helps you move up fast, whatever you really practice a lot at gets a multiplier bonus at level up time.
for instance, my assassin practiced sneak (major) and athletics(minor) like crazy. when our first level up came, lo, she had x4 to her sneak. so when i placed one point into it to levelup, she actually received +4!! i didn't get a multiplier on her athletics (cuz its a minor skill), but she was practicing it so much, that i have been getting sometimes 2 levels at the same time!
with your magick, i have heard that you can make "trainer spells" that summon items. if you set it up right, it trains you really well, but you don't spend your magicka super fast.
since i'm not magic oriented, i really don't have any details, but i'm sure some of the mages here will know what to do!
so, just keep trying hon! it will all start coming together soon.
V***V