HE KNOWS

Exactly that part was soo tricky i was like damnnn bruhh ..... he (seolhyun) knew all along that he was a female lycan, then why did he lie to hwa thats the big question arising in mah mind

To protect Hwa.

Hwa got hurt a long time ago because Seohyun had marked him or Hwa marked him idk. But also this is weird. Isn't Hwa supposed to be a full vampire? I mean both of his parents are vampire correct?

His mom is a hybrid. He was a lycan when he had Hwa and was turned into a vampire after so they could be together forever.

Uhm no Seolhyun doesn't know he is a female lycan tho he still remembers what happened in the past about marking Hwa, that is because he begged his uncle Ino not to erase his memories. So, Ino decided to hypnotize Seolhyun and just made him believe he's a male lycan when in truth he is a female.

See bruh hwa is a hybrid i.e half vampire and half male lycan bcuz when his mom gave birth to him he was a lycan and later he transformed into vampire it was in the last ep of season 1 the reason why he became a vampire is cuz he want to live forever with his other half

Yeah, exactly! And to follow on your comment, I wanna add that, "Mark me as a female Lycan" is obviously something he's saying out loud wishing it to be true. Hwa also knows he's a female lycan because in chapter 75 he called Seolhyun "big and cute female lycan". Seolhyun is feeling guilty about about their childhood past and the fact the he's misleading Hwa into believing that he's a female lycan (but in reality he is female).