Hi, worry it took me 3 days to get back to you, I am preparing for a workshop in Europe. Did you try testing your implementation on the NWC tester? https://supertestnet.github.io/nwc_tester/

I recommend doing it with a backend that definitely works first, like this one: https://supertestnet.github.io/bankify/

One you have seen it work with a known-working backend, try it with your backend. Inspect the code bases to see what you are doing differently from the known-working one.