HCG After Ectopic Surgery

I had a laparotomy on wednesday morning after seeing no sac in the uterus and having levels of 2800. I should have been 9 weeks. Never had pain but did have some spotting the week before. Doctor removed the ectopic from my left tube, saving the tube and told me it flushed. She seemed confident she got it all and wants me to get bloodwork in a week. I was wondering how long it should take for my levels to get back to negative? It seems, from what I've seen on the Internet, surgery should drop levels faster than methotrexate. Wondering what experiences you guys have had.