Summon Monster has a duration of one round at first level and the monster gets to attack the turn you summon it. So does it get another attack before it winks out? If not I'm gonna try to place it where it'll get an attack of opportunity too.
Stop using summons for melee and all will be good.Elethiomel I believe has it correct. Basically even if you are a specialized conjurer, you're better off doing other things until you hit a minimum of 3rd and don't forget Mage Armor is a conjuration spell. So you can take than as your specialization bonus spell.
SM I at first level is a waste of a spell.
BTW Celestial Bison at SM III is your first really good summons.