confused and worried

So I took a home test on the 20th of August, got a very clear positive so I went to the doctors and they confirmed it with another urine test. I have booked for bloods on Tuesday and I've taken a few tests in the past few days and they have been very very faint, took another one this morning and it's slightly darker? Is this normal. I'm just worried because my first test was so clear and these all have very faint lines.