I know 2 people that respond so terribly to poison ivy, that they need steroid pills.
This one guy in grad school got it SO BAD!!
He started wearing long sleeve button down shirts with everything buttoned down! Even top collar button. In the Texas heat. And finally one of the grad students asked him what was wrong... he told us that he had had a small spot, not sure where, but it just kept spreading all over him. We made him show us.... he didn't fully strip down... but it was all over his arms and up his neck! It was super red, flaky and oozing blisters. All of us told him "DUDE! THAT IS BAD! GET DRUGS!!"
Anyway, I am not sure what he had tried. I know he said he was spending lots of time soaking in an oatmeal bath.
With all that said, yours doesn't sound that bad. But watch it and if it keeps growing, or starts looking like your skin wants to curl up and die... you might need a round of steroids. When it is that bad pills are way more effective than creams.