You do still have a higher risk of developing gestational diabetes, just based solely on your already having had this during your first pregnancy--the risk does increase with subsequent pregnancies. However it is not 100% in either direction, yay or nay. The best thing you can do, as suggested by "melaniemac" is to optimize your health before you try to conceive. This does mean losing a few pounds, exercising regularly, eating healthy foods that are high in fiber. Be sure to keep a close eye on your blood sugars throughout this time. If you do develop gestational diabetes again, remember that you did just fine during your first pregnancy and with good care and vigilance, you will again.
It is not just weight and height, it is also a bunch of other factors. I would say that if you got pg today, you would probably have gestational diabetes. Stress does play a part in bringing it on, but being pg is stressful no matter what.
First, you should get in shape and lose some weight before you get pg if you can. Your Body Mass Index is right there on the edge of overweight, but if you have thick bones and a sturdy frame, you can have a little higher number. Since you have already had gestational diabetes at a lower weight, you should try to lose 5 to 10 pounds first.
Second, be sure you eat the right kind of foods- high in fiber and low in bad fats and refined carbs. Take a multivitamin and practice some stress reduction techniques like yoga or meditation.
If you get gestational diabetes, be sure to see your doctor on a regular basis and take your insulin as needed. It is dangerous for the baby to avoid the insulin, but is safe to take if you do so as directed by a doctor.
Good luck to you