What’s your junior dev salary in London?

Hi! I started my first tech job after bootcamp. I did internship, then got associate position and now promoted to Engineer I. I live in London and I feel like I’m underpaid (or my expectations are too high). Looking at glassdoor, junior devs in London earn 38k on averadge. I was earning 30k as an associate and after having a promotion I was hoping for more but got offered 35k with no option to negotiate. Am I underpaid or my expectations are too high and it’s the market right now? How much do you earn in London?

I’m a backend dev.