When did you first have a positive pregnancy test?
Do you know what your hcg result was in numbers?
Do you have any pain or spotting? Thank you.
I'm afraid there isn't much chance that this is a normal pregnancy. A sac should be seen 13 days after a positive pregnancy test.
The presence of a sac in the area where you previously had an ectopic pregnancy is ominous and suspicious for another ectopic.
It will help some to know what your hcg level is. If it's significantly high, then a pregnancy should be seen, and if it isn't seen inside the uterus, that's highly suggestive of an ectopic.
If you do have another ectopic, it will sometimes go away on its own, and can often be treated with medication. Best wishes.
Many ectopics today can be successfully treated using methotrexate.
However, if surgery is needed, it could be done before you have any pain.
Some ectopic pregnancies will disappear on their own and need no treatment.
Unless your doctor gives you a good reason why you need surgery, I would try to get a second opinion. I don't know how difficult that might be in the UK.