Help! Tests taken 7-9 DPO, should my test lines be darker now if I haven’t missed my period?

I took the top test with water so I could have a stark white negative.

The first positive I got the 19th with FMU, 7 DPO. The next two faint bfps are from 8 DPO with FMU. The last test was from this morning with FMU.

Should the lines be darker now that it’s been 2 days since I first got my positive? Or does that take awhile since I haven’t even missed my period yet?