Imbadatksp

By sliding i mean it yaws over about 10 degrees, then and by that point ive lost all control. I cant bring it back around, and its not my gravity turn. I forget the name of the engine but it is one if the first two LVTs you unlock. No SRBs.

Please help! Every single rocket i build slowly slides off to one side, no matter what. Everything is in line, center of mass is in the bottom middle if my rocket, i am using fins, sas is on, and im not touching the engine. I have no idea what is going on and how to fix it. The game is nearly unplayable because i can't reach orbit to collect science so i can't unlock halfway decent parts. Please help