Options loss question

I know I know…. I shouldn’t even be trading options if I do not fully understand, but I am an idiot and a glutton for punishment. I made my first options trade earlier in the week. GME 14.5 3/28 Put 5 contracts at 1.28. Bought prior to earnings as I thought the earnings were going to be horrible. Well the stock opened the next day down 15% . When I closed my position at 9:35 am I had lost $10. Can someone explain to me what happened and how I lost $ even though the stock went down substantially. Thanks