That sounds like an unusually unlucky start. I don't think I've had a start in Stellaris where there weren't at least three or four +2 mineral sources in my starting system, which should easily push you above +10 when you add in the production of your homeworld. Mind you, you should savour this point in the game--there will come a point where you're getting hundreds of minerals per turn and have no idea what to do with it all!