Hi The protected sex is very low risk for herpes and syphilis and if no part of your pubic mound area made no contact with hers, its zero risk. The oral you mention on her is zero risk in the real world as takes some what prolonged rubbing contact to get herpes or syphilis.
So first - let me correct something. A chancre is a syphilis sore, which is different than a cold sore. Also, your cut could have been just an infected cut, or it could have been a cold sore. Unless you had it cultured, you don't really know which it is (though I highly doubt it's syphilis).
Canker sores are usually inside the lip, and are usually white. A chancre is round and red, and also painless. If you think you have a chancre sore, call your doctor and tell them you think you have syphilis and need to be seen sooner than a week. Chancres usually take about 3 weeks to appear, so if you've had it for awhile, it's not a chancre. You can google chancre sores and see what they look like vs what a canker sore looks like.
Okay, so that said...
So receiving unprotected oral sex puts you at risk for syphilis, genital herpes type 1, gonorrhea and NGU.
Syphilis isn't that common, and your partner would have had to have a sore in their mouth to transmit it. You wouldn't see symptoms of this for 10-90 days, but the average is 21 days, and you'd get a sore called a chancre. This doesn't cause burning, pain, discharge, etc. You can test for this at 6 weeks. If you get symptoms, but test negative at 6 weeks, test again at 90 days, and get to the doctor as soon as you see symptoms.
If you don't already have herpes type 1 (think oral sores, like cold sores but not canker sores), then you could get genital herpes type 1 from receiving oral sex. This can happen even if the person performing oral doesn't have a sore, but it's more likely if they do. The time from infection to symptoms is usually 2-12 days, but the average is 4 days. You can test for this now, and then again at 4 months to make sure you don't have it. If you test positive now, it's a pre-existing infection that you had before this encounter. About half the adult population has this, and 90% don’t know it. Ask for a type specific IgG blood test.
You'd see symptoms of gonorrhea at about 2-5 days, and this would usually be a discharge, burning, etc. Some people don't get symptoms. You can test for this as early as 3 days, but 5 days is better. You can have a urine test or a swab test.
NGU is an infection in the urethra that is caused by anything other than gonorrhea (nongonococcal urethritis urethritis, sometimes called NSU, for non-specific). This can be caused by normal mouth bacteria entering the urethra, and the symptoms and testing times are the same as gonorrhea.
You ejaculating doesn't affect your risk at all. It affects hers if you have something, but not yours.
Performing oral sex on someone with a vagina puts you at risk for gonorrhea and syphilis. The chances of getting an oral STD from oral sex on a vagina is lower than oral sex on a penis because nothing is going in your throat like when you perform oral on a penis.
You have no risk for HIV.