Many years ago, I stripped and painted my kitchen cabinets with the same latex paint that I used on the walls and top-coated them with a polyurethane varnish, hoping that the finish would hold up better in that environment. It did, but the polyurethane had a slight amber tint not really noticeable at first but became much darker as time passed. If I was doing it again, I would definitely use as water-based product as they don't darken in time.
Is the paint that you used made for painting wood cabinets and furniture? Several manufacturers advertise their product as having been developed for painting cabinets, and you may find that a poly top coat is not required. If you do decide to go with the extra protection, you may want to check with the paint manufacturer to make sure that the two products are compatible.