I lied at Meps about smoking pot a couple of times in the past. I need advice on my best course of action.?

HI, I have recently been through meps and signed my contract with the navy. I was honest about everything, my criminal history and my medical records. However when asked about illegal drug use i said no to all of it but in reality i have tried marijuana 3-4 times over the past 4 years, something I didn't think was a big issue but it has been weighing on my conscience. My job is in intel and will require a security clearance. At the time i didn't believe anyone would ever find out about my "experimentation" with pot but with the BI i feel it may come up later on down the road. I want to come clean and i realize doing so will probably cause me to be discharged from my DEP but i feel its the only way to clear my conscience. I plan on telling my recruiter this later this week or next week but i would like some advice first. I do not wish to be discharged as I really want to serve my country with the navy. Can anyone tell me their experience with this or the best course of action I can take.