I can definately understand your nervousness. However, when you say that it doesn't show up on the MLS, what website are you looking at, and also, did your realtor present the offer? If the number for the listing doesn't show up anywhere, the reason can be discovered by your agent using the MLS and checking the current status. ALl listings have a current status that may not be available to the pulic. The Key is your Realtor! You don't say that you are using a Realtor. Did you make the offer yourself? All this needs to be discovered before all your questions can be addressed.
Good luck to you, and if you need help, well . . . . :)