Im a 300lb woman-walk 2-3 miles 5 days a week and calorie intake is 16-1800 and not losing weight still.. HELP?

I dont no what else to do. I've been walking for 6 weeks now and eating 3 healthy meals a day wirh a fiber plus bar and greek yogurt for snacks. At night I have a weight watchers smart one desert cup. I'm trying so hard and nothing has happen. Am I eating to many calories or not enough?? Do I need to walk more? Have of my walk is at a uphill grade. This is an exsample of what I eat...breakfast 2 eggs with a little cheese and saus or turky bacon or oatmeal, luch is a salad with tomatoe, red onion, some kind of meat if i have it and little ranch, Dinner- chk or fish and veg or 2 veg maybe a salad or small red potatoe and 1 cup of milk. In between are my snacks..Please help me...I need to do this for my health and kids. Thanks Lisa