Different tests have different amount of dye in them, and give differing strength of positives. Even when using the same type of test throughout, there can be big variation in the darkness.
I have had many (many) miscarriages, half of which were early at less than 6 weeks. The bleeding no matter whether early or late mostly started once the tests turned negative.
If you tested previously and today with an frer, and the lines were significantly lighter today, I would first question whether:
- before testing you had drunk more fluids?
- if you tested at a different time of day, for instance in myself, I get darker tests with second morning urine than first morning urine.
- are you certain the brand of test used both times is identical, and from the same packet/batch number?
If you answered 1 and 2 with no, and 3 with yes, then and only then would I think that there is a possibility of it being a chemical pregnancy/early loss.
IF it is a CP or early loss, then you will probably find that it is just like a late period when the bleeding does start.
As for contacting the doctor, they will not do anything, and if you have a negative on an frer, then you would get a negative on a doctors test, and therefore it would not even be noted as a early loss, so would be of little use seeing the doctor. Sorry.
However having said that, it is very possible since you used a different test last week, that it is not an early loss at all.
I see you have re tested and got a light rather than negative test. I think that you have to back away from the tests. If it is a CP/early loss, then you will have bleeding soon, if not, then you have every reason to continue to have hope. I would suggest waiting til midweek, and if no bleeding before then, then re test with frer and see what shows then.
Sorry you are going through this, and hope you are able to distract yourself from it all for a while.