As a general rule the airline cannot cancel your reservation if you don't reconfirm. But as a general rule I always reconfirm my flight by calling the airline with my booking code to confirm that my special meal request has been entered and that my seats are reserved. I also confirm the flight departure time, what terminal its leaving from etc.

Be sure your Travel Agent confirms your seats and request an aisle or window. If you want to request special meals do so with the travel agent she or he will tell you if they are available. Also sign up for the Frequent Flier Program if you don't have a number. If you do have the agent enter it into the reservation for you.

Be sure your tickets show "OK" under the Confirmed portion of the itinerary.

Here is a sample itinerary.

Smith/David Jones
Smith/Rachel James

Lufthansa(LH) Confirmation Code 342JKY
Amadeus Confirmation Code(3QYJDK)
Ticket# 00122099883

LH 458 Departure Munich(MUC) 16:00 Status:OK
Arrival San Francisco(SFO) 19:05
Airbus Industrie 340-600 Jet
Your Check In is with Lufthansa
Latest Checkin Time: 14:00

Services:
Meals: Meal,Meal
Movie:Yes
Seats :

Smith/David 33A
Smith/ Rachel 33C

Special Requests

Smith/David VGML(Vegetarian Meal Requested)
Smith/Rachel VGML(Vegetarian Meal Requested)

Hope this helps.