Your lamp is fine for now, but I would pick up something that gives off UVB rays when you get a chance. In the summer you can just put your turtle outdoors to bask a few hours a week. Then you wouldn't have to worry about what kind of bulb you had during the warm months of the year.
In short, reptiles convert UVB rays into Vitamin D3 which helps them utilize calcium. They do benefit from UVA rays but they aren't that necessary. Plants need UVA rays more then reptiles do.