There is a lot of information on short sales and a lot of different opinions. I am sure you will experience them with this question.
Please keep in mind that each owner and property has to be evaluated by themselves. The first thing you need to do is determine if you qualify for a short sale. I say this because you had until now not missed a payment. You MUST have a financial hardship to qualify for a short sale. You must have had something happen that is like a loss of job or accident or a decrease in pay or serious health problem. These are just examples. The point is you have to be in trouble financially to do a short sale. You can't just sell the property for less than you owe because you no longer want to pay. I am going on and on about this because so many think that if their property is worth less than they paid they can do a short sale and that is not the case.
So number one question.....do you have some type of financial hardship that qualifies you for a short sale? Moving and getting married are not on the list. (Unless possibly you have to transfer) Speak with a local Realtor as you will see below.
When you say under water on your mortgage what do you mean? If making your mortgage payment is keeping food off the table then listen to the attorney's. I am in Florida and you need to talk to and listen to people from your State as some laws may be different.
If you are still with me, then find a local Realtor. Talk to several of them.
1. Find out who knows about short sales and how to get them closed - legally.
2. How many short sales have they completed and what is their process.
3. Once you have picked a couple of Realtors, set up appointments with them and gather all information and sit down them and tell them your situation financially. They will be able to tell you if you qualify for a short sale.
4. Pick the Realtor to help you and get the property listed right away.