did a lot of work with no permit

[Tyco Bronye]

I bought a house that was not in the best shape about 4.5 years ago.  It is three floors total with a walk out basement. The first project I did, I pulled a permit for which was to completely replace the electric main panel and replace the large main wires that go out to the roof.  The reason I pulled a permit was because I did it myself, and this was the first time really working with electricity, so I was concerned over the safety.  I wanted to make sure it was correct so I did not die.  This was great because I basically had this professional (inspector) keep coming back at no additional charge until I had it completely up to code.  After that I have been consistently improving my house over the past 4 years, and never even thought of pulling a permit of any of things I did.  One of the first things I did was make the basement into a space where I could live, and then my plan was to rent out the upper floors as a separate unit.  The basement consisted of a large  room about 340 square feet that was finished when I bought it in that it had drywall on the ceiling and walls, and had an unfinished area that consisted of the electric panel, water heater, furnace and washer/dryer.  I made a kitchen, (gas stove, sink) added electrical outlets and ceiling lights and  I finished off the walls and ceiling with drywall, and also added a full bathroom,(tub, sink, toilet).    My house is in middle of a hill, so the backyard was unusable being just a hill that's maybe around 30 degree angle so I put a short retaining wall about 2 .5 feet tall so I could flatten out the area close to my house, I added dirt, cat 5 gravel. and did a bunch of pavers, I also added concrete stairs, going down the hill that sit directly on the hill. I flatted out the area at the bottom of the hill with a concrete paver patio that is about 300 square feet.  Finally, I added indoor living area to the walkout basement.  When I first bought the place the walk out basement entrance was under a 13 ft by 13 ft three season porch, that sat on pillers that was added before many years before I bought this place so I decided to box the area underneath it and make it an additional room for the basement, I figured I may as well since I already have a roof for the add on, that being the floor of the three season porch right above it.  Everything should be to code on the add on, I dug and poured a 4 foot deep foundation since I live in cold climate. I put in windows and electrical outlets and ceiling lights and it has been my finished bedroom for awhile now.   

Now I'm finally getting close to done with this big project that I've been steadily working away at while living here with my spare free time over the last 4.5 years, and I'm interested in getting a renter for the upper 2 floors.  Now I'm worried about getting a certificate of occupancy from the city to legally have renters.  Now it's basically a duplex since I have two living areas with their own bathroom, kitchen and washer/dryer.  I only really became familiar with permits after listening to the bigger pockets podcast, and now I'm scared after I googled it and read about possible severe consequences.  It's weird because it always seemed like one of those issues that if you do it, it's just a headache and if you don't it's not big deal, I was a service plumber for a few years and I have never known anyone to pull a permit on waterheater replacement even though technically it's required and I've never known of any plumber getting a permit for anything other than brand new construction homes. Even in the realm of plumbing, you are technically "supposed" to have a license and 5 years experience in order to go work on peoples homes by yourself but the reality is new plumbers are sent out to people homes with a month or 2 of experience. It's also weird that in all the hundreds of times I have been to home improvement stores getting advice from workers on how to do projects, never once has anyone pointed out the need for permits.  How would a common homeowner know that he has to get a permit in the first place?

I'm wondering what I should do at this point.  I asked a friend who has a rental and also turned an attic into an additional room and never got a permit for it and he said I should not worry about it because the certificate of occupency person just looks for working windows with screens and working smoke detectors etc.  The other thing I'm worried about is home owners insurance if there was a fire would I be covered since work I've done ( adding outlets) was done without a permit

I would like to own this house and have no plans to sell it ever and always keep it as a rental

Any advice?  Thanks