In this work, we propose a novel self-seeded WDM-PON topology. Unlike previous works, in our case, the self-seeding occurs in RSOAs located at the OLT, allowing upstream transmission based on carrier remodulation at the ONT. Thus, a single wavelength per user can be employed for both traffic directions while eliminating the need for an external broadband light source at the CO. A maximum bidirectional 2.5 dB power penalty for a BER of 10-10 was obtained for an injection power level of -22 dBm into the ONT RSOAs. We also investigate the tolerance of downstream BER to downstream extinction ratio (ERD) and self-seeding power (Pss), as well as analyze the impact of upstream extinction level (ERUP), injection power (Pinj) and ERD levels on upstream BER performance, on symmetric 1.25 Gbps OOK transmission over 20 km without DTLA and FFCI mechanisms. We have successfully demonstrated downstream error free transmission (BER of 10-12) for an as low as 3.5 dB.