Ectopic unknown

Anyone that could possibly have any advice for me would be great. On 2-2 my doctor and myself thought I miscarried at 5 weeks, however, my HCG levels are now climbing.. its only been a week and half so too soon to see a “new” pregnancy on an ultrasound... but yet my dr keeps throwing around an ectopic pregnancy... in 3 ultrasounds she hasn’t seen anything though, nothing in either tube and also nothing in my uterus... does it anyone know if it’s possible for an ectopic pregnancy to never be “found” or confirmed? I just don’t see how I could make myself go through with the methotrexate medication without a for sure confirmation it is indeed ectopic... anyone gone through this? Have any type of experience with this? I’ve spoke to 2 doctors... the one that wants me to chose the medication can’t find anything the other doctor said my HCG would be through the roof (which it’s not) and that I would have pain, which I’m not... any help I would love