Sorry to hear that you are worried about having a dry socket after having your wisdom teeth out and I recommend that you visit your oral surgeon
who can examine you. When you have your wisdom teeth (or third molars) removed, there are many different techniques to close the surgical site. On option is to close the mucosa upon itself if possible to ablate the defect left by the missing tooth, and close any potential dead space where food or debris can collect. Depending on the technique used by your oral surgeon, or dentist, there may, or may not, be a potential space where a blood clot can form within the fossae where the third molar was. You have correctly identified that a 'dry socket' is when there was at one time a blood clot within the fossae of the third molar that has been dislodged for some reason. There are many different possibilities for why this clot could dislodge, swallowing and causing negative pressure being just one of them. In many cases if the clot within the tooth socket is dislodged, it can be quite painful, as there are nerve roots are exposed and become irritated. There is no way to tell for sure if you have dislodged a clot other than by examining you, so it is hard to tell if you will develop a 'dry socket'. I recommend that if you develop a lot of pain, and an acute increase in pain post-operatively, that you set up an appointment to be seen by your oral surgeon or dentist.