Oh dear, that's the same problem i had with the last tote bag i made a couple weeks ago, it kept gobbing up underneath, the only saving grace was that the lining of the bag covered up the mess. I've been doing straight sewing since, and played with my tension a bit, its doing good for straight sewing, im thinking of trying some freemotion again on just a scrap piece. I find it does it sometimes too if i'm just moving the fabric a bit too fast. Hope it works out for you