Implantation Bleeding

Hey! I'm new to the TTC world! Baby number 1 was a pleasant surprise. 
Now we're trying for number 2! 
I'm 13 DPO
AF should have started on the 9th but she didn't. Took tests BFN. Took one Tuesday BFN. I took them in the afternoon too which I know I shouldn't do but in my sleepy stage I forgot first thing in the am. 
So yesterday about 3 o'clock pm I went to the bathroom when I wiped the tp was tinged pink. 
It has been ever since without at drop on the panty liner I put on in case it was AF.
My period has been in and out this last year due to the impala on bc and it continued when I got it out in January. 
But typically when mine starts it starts there's no nice little barely there grace period day. 
I guess my question is has anybody had implantation bleeding that lasted for 24 hours? It doesn't show up every time I go to the bathroom and wipe just some of the time. 
Thank you in advance!!