Congratulations!

A faint BFP at only 11dpo is all that I would expect. Some women don't even get a BFP that early! Implantation typically occurs between 7-10dpo, so you have only been producing hcg for 1-4 days. It takes a while for the levels to rise enough to produce a dark line on a HPT (although, how long varies by brand). Just because you typically have a short LP, doesn't make implantation occur any earlier. Your tests should progress at the same rate (by dpo) as someone with a 14 day LP.

Saying that AF is 2 days late is misleading and may cause you some unnecessary worry. Most women 2 days past when AF is due are 16dpo and you would certainly hope to see a dark line on a HPT at that point (again, depends on the brand). Try not to worry about when AF was due and just count the dpo. Any line at 11dpo is a good line!

FX they get darker for you over the next few days.