It's hard to say without detailed measurements but 54cm sounds a bit
small given your height. My girlfriend's 5' 10" with 34" legs and feels
tight on a 56cm top tube and a 90mm stem. She did feel streched out at
first but that's a temporary thing. I'm 5'8" with 32" legs and find a
54cm top tube with a 110mm stem just about right. Everyone's different
though so for the first bike either buy something REAL cheap so you can
sell or toss it if it doesn't fit or get an actual fit- not just some
dude's guess.