Making milk 9-10 months after I stopped breast feeding

I stopped breast feeding in sep/oct of last year and dried up pretty quick. Over the last few months I’ve been struggling with bloating and acne. I have had an IUD in for a while and there is really an extremely low chance of me being pregnant. I am lightly bleeding (think it’s a period) and I’ve tested negative and yet my boobs have been hurting, growing and getting fuller, and having that let down feeling. Today I squeezed them to see what happened and milk came out! What is going on???