@Riger I think you're thinking too much into real guns for a manhwa.
However, if it was a bullet to the head, she would be dead immediately, she wouldn't be able to talk afterwards.
ch. 62, p. 19 looks like blood is flowing out from the blood stain between right collar bone and chest. (the blood stain is also there on the page you talked about.
but most likely, the additional wound would just be explained to be somewhere on her black shirt, causing goomoonryang not to notice it. (he would notice it on her skin and, since he holds her head in his arm, he would notice that too)
extreme bloodloss is probably caused by bullet to the aorta.