I think you need an antibody test that gives you an index value – it is a number associated with the test results. Immunoblot does not give an index value. The quest labs and labcorp labs do give values. You could arrange for testing with one of these labs over the internet. There are some false positives on these tests and your history suggests that that could be the answer here. The other possibility is that your girlfriend is infected and infected you though the timing seems less likely. Has she been tested? If not, she should be.
There are no cures for herpes at this time so don’t be lured into buying products or doing things that suggest that there is a cure.