Mistake 1 was you rode before you were comfortable with clipping out.. Most will tell people new to clipless that they should practice somewhere safe and where there is soft landing so that any fall will not really hurt. Practice in grass, in your garage with a soft mat on both sides, on a trainer etc...
Don't take clipless out on a road, gravel or whatever ride until you are comfortable with clipping out. Practice, practice, practice.. We've all been there and there is no shame in falling over in the grass when practicing.
Once you get that muscle memory down, clipping out becomes 2nd nature and you don't even think about it..