Post meal sugar of 154 right after meals is considered normal. Even in absence of diabetes, the sugars tend to remain elevated for up to 2 hrs post meals. It is highly likely that you’re not prediabetic and have nothing to worry about. However, one sugar reading is not enough to diagnose or exclude pre-diabetes definitely . It only gives a snap shot of your glucose levels. Because you are over weight would recommend further testing to exclude prediabetes, by checking HbA1C in lab ; with fasting sugars and fasting insulin levels ( following 8 hrs overnight fast) and sugars 2 hrs post any meals. Insulin levels will also give us an idea if you have insulin resistance which can predispose you to develop prediabetes