It's not bad to go for 12 stam bonuses, you might hit the socket in your helm. I also assume you mean 10agi/15stam since I'm pretty sure a 10agi/15str gem doesn't exist.
Get rid of 16 defense to cloak, replace that with 225 armor and put either 240 armor or 18 stam on your gloves (leatherworking kits). I'd also say 18 stam to shield.
Most importantly though: GET RID IF EITRIGG'S OATH ASAP! Essence of Gossimir would be preferred to it. If you don't have "the black heart" yet then go farm it.