Hi Becky, Im sorry you are still confused, I will try to explain it better (it might help with your current and future pregnancies!)
All pregnancy length is measured from the date of your last period, so when the doctor says you are 23 weeks pregnant, they mean 23 weeks since your last period. So when you had the blood test saying 'five weeks', it was saying you are five weeks pregnant, following the usual calculation of 'since your last period', based on a 28 day cycle, which you apparently have.
Now, the digital test you did doesnt measure from your last period, because they have to go on the physical measurement of HCG concentration in your wee, so the test says it measures from conception. Thats why it is called a conception indicator. Conception happens about 2 weeks after your last period, so you have to add about two weeks onto the number of weeks displayed on the test.
So, if the test said it was 1-2 weeks since conception, you were 3-4 weeks pregnant (2 weeks + 2 weeks = 4 weeks). This agrees with the blood test a few days (about a week?) later, which put you at five weeks pregnant. So the test and the blood test showed the same thing - five weeks pregnant.
Basically, by the time you find out you are pregnant, you are already 4 weeks gone, as it is a month since your last period. So its impossible to be 1-2 weeks pregnant, only that it is 1-2 weeks since you conceived.
The commercial website has a really nice table that explains it clearly, here , go to the bottom of the page.
I hope this helps - in fact, the digital test did quite well, but if you are confused by them maybe its best to avoid them.
Take care.