If I believe I contracted mono three weeks a go but show no signs, will a blood test be positive if I have it?

Question

My girlfriend was visiting me exactly 3 weeks a go, and she tested positive this week. I'm paranoid I have it, but am not sure if it's worth getting a blood test until I have serious symptoms. If I get tested now, being that I would have been infected three weeks a go, would the test show that I have it, or is mono undetectable until you have symptoms? Thank you for any response.

Answer 1

Best to get tested and put your mind at rest, or be told you have it? Either way better to know, then you can planning your recovery.