I have been unofficially supporting my child for 5 years in every way ( financially)
You need concrete proof of any and all payments. In Poland, if there isn't a receipt or other written/printed/printable evidence of a payment, it didn't happen. Unfortunately.
My ex has told me if I apply for DNA or go to court she will make sure I never see my child anymore.
You really do need a lawyer, even the CAB may be able to point you in the right direction.