two girls and a boy maybe?

red/buff pekin chicks aged 5 weeks. Not at their most attractive bless'em but cute all the same. Any ideas on sexing? My guess is large combed is boy but are other two girls?  I know they can trick you. One was bigger and more feathered from the start. They have fitted right into my little flock (out with them for late afternoons under Mum's watchful eye.