It doesn't matter for what duration you have had sex, transmission is possible even if the sex was for one minute. If you have little cuts and tears on your penis and there is HIV involved, you will get it.
I am not trying to scare you at all.
Blood is one of the fluids with lots of HIV in it. That concerns me that you had dried blood on your penis. But then again the blood was dried and could not carry live HIV..
Oral sex is a lower risk activity especially for the person receiving. But you performed on each other. Depending on your oral hygiene it is possible to pick something from the sexually transmitted diseases.
I recommend that you wait 90 days from the day of supposed infection and get tested for HIV for your own peace of mind. Also, test for STDs as soon as possible.
During the waiting time, please do not involve yourself in risk behaviour.

for writing in.
Muthoni (Mson)