What is my chance of getting herpes?!

If he didn't have any cold sores at the time you had oral sex then you don't have a big chance of getting herpes from him. People usually show signs of herpes with in 3-30 days of contracting it. If you don't have symptoms yet then you may not have it. Most people contract cold sores during child hood by being kissed by some one that has cold sores or fever blisters.
You can get a blood test done but if you have ever had cold sores before (they are very common to have) you will get a positive result. All the blood test tells you is if you have it, not where to expect a break out.

You should be fine. Generally if you contract herpes, you'll have symptoms within a month (burning, itching, redness). If it's been six months since your risk, you're probably fine.

http://www.scarleteen.com/article/infect…

You can't get herpes unless it's actually on his lip. Herpes spread through skin to skin contact. If he didn't have a outbreak at the time you most likely safe.