Is it possible to develop gestational diabetes after the gluclose test? I developed the symptoms after and baby was 9lbs 1oz with jaundice.

Yes. You can develop it at any time during pregnancy and can develop dm2 after delivery...Depends on weight gain, diet and genetics.
Timing is important. Ob providers do the best job they can to determine how far along a pregnancy is and to do testing at the optimal time. Sometimes, however, a condition might become apparent after a test is performed. There are other reasons for having big babies and for babies having jaundice, however. Records from the pregnancy, nursery, and pediatrician help with future pregnancy management.
Yes. The 1 hour and 3 hour "sugar" tests screen for gestational diabetes, but they are not 100% perfect, so the answer is yes. However, that doesn't mean that your doctors did anything wrong. In a patient with your history, many doctors to give you a sugar test earlier in the next pregnancy. Consider asking them about that.