After looking at the lining, I believe your bag is genuine. I believe it's the old version of the Jet Set Macbook Tote. The style has been changed & it's now called the Jet Set Multi functional Tote. I believe these totes were made in Vietnam. I also believe these totes were originally made to be sold in Apple stores. I'm not too concerned about the lining being light. I have seen MK bags that are darker bags but have lighter lining. The seller has low feedback & doesn't seem to have much experience with designer purses but what feedback they have is positive. Sometimes you buy authentic items for low feedback sellers. Everything else looks good on your bag & I see no red flags.
Enjoy your bag.