The right way it would be: "Me sentí emocionada porque estaría viajando a España la semana siguiente".
Me sentí = I felt something (by myself)
Me sintió = HE/SHE felt something (about me).
It's like in English, for reported speech, you're talking about something that happened in the past (I felt excited) and you also mention something that was going to happen probably in the past (conditional "I would be" = "yo estaría").
On the other hand, if what you want to express is something as, let´s say, "I felt excited...(past) I WILL be travelling... (future continuos, something that is going to happen), then the right way woul be:
"Me sentí emocionada por que estaré viajando a España la semana próxima" (past - felt, future - will be).
Hope it's useful, have a nice day.
Frank, bilingual teacher from Spain.