I'm 24+2 today. My 3rd pregnancy but 2nd was ectopic which I naturally miscarried...
I spotted in my first trimester in my first pregnancy but nothing really thereafter and our son just turned 3.
With my ectopic I spotted for 2 days and day 3 was about half a teaspoon then got worse til the embryo passed fully. I was also quite unwell during the process.
This time I still have spotting of red blood now but baby is doing well.
What I have learned throughout....
Red blood is fresh blood. Brown is older that may be just clearing from last of implantation. Use only pads (not tampons) as it's far easier to judge how much blood loss there has been.
The blood vessels and muscles etc. in the whole internal area, down there, are swelling and expanding in preparation for baby so anything from sitting down hard to sex can cause them to result in spotting so unless it's more than short spells of spotting of fresh (red) blood I don't worry about.
The fact that you're lines are getting darker is a big positive. With my ectopic, after the miscarriage started, the lines slowly got weaker. hCG levels only continue to rise til around 12 weeks so if the lines getting stronger, the levels should be too and as I was less than 4 weeks when I lost the embryo and the lines got fainter it tells me all is still fine for you.
The only other thing you can do is speak to your EPU and keep an eye on things.