Go ahead and get a consultant if you think you need to!
The only thing about a consultant related to ISO 14001 is if he/she is competent (4.4.2), is aware of your policy (4.2), you have an operational control and monitor or measure key indicators if they are or present a significant aspect (4.4.6 & 4.5.1), that you identify the aspects they bring into the mix (4.3.1) and amybe 1 or 2 other things.