If your agent hasn't already done it, have them set you up on an MLS email search so that when a property comes on the market, you will get an email notification the next morning. This will keep you in the loop for a "hot" property.
You should ask her again to explain why she doesn't think you should go forward. You need to understand exactly the situation. When I work with a Buyer, I generally recommend waiting for the 1st offer to fall through - then jump on it. If you put a back-up offer in, I believe all you do is provide the seller a more secure deal with the first buyer. If there are any problems and that offer falls through,
In Massachusetts the process is a little different from what was previously described. Excluding bank-owned properties and short sales, the first step is an offer. Once it is accepted, the seller can choose to accept back-up offers (this is indicated by a special symbol on MLS) until the P&S is signed, but these are not presented to the seller or negotiated until the first deal falls through. Then back-up offers are next in line.
In your case it sounds like the P&S has already been signed, which is unusual because it is almost always signed AFTER the inspection is done and any issues resolved. So I'm not sure exactly what the status is.
If you are able to put in a back-up offer, you can alway withdraw it at any time prior to its acceptance. But I would make sure you have a real estate attorney review your offer if you do submit a back-up.
Hope this helps,