Thanks all three of you for your opinions, it is greatly appreciated having some outsider input here! ☺
I didn't realise positive HPT lines could vary and change so much. I just thought the way they come up orginally is the way they stay!
I don't want to get my hopes up too soon though, to only be disappointed with another negative. So, I'll wait it out a few more days I think, retest with a First Response using my FMU (note: All 3 tests, including the pictured one were in the afternoon/evening) and then head to the doctor's hopefully with another 'positive' in hand ☺