LP how many days????

Dee
I've noticed I've had a short LP, last cycle was 8 days with one day of spotting. 
This cycle I started vitamin b complex and got to 9dpo without any spotting. 
On 10dpo I had what looked like AF starting but Pink and only on the toilet paper each time (but quite a lot). 
11DPO- pretty much the same as 10DPO but now red blood (temps still up but slowly dropping)
12DPO- today, same as yesterday, still red but temps dropped almost to coverline
So is my LP 9 days, 11 or 12 days? 
I would assume 12 days as it's not full flow yet but implantation couldnt occur after red blood has shown could it?