Don't worry, you went the right way. Laminate is thicker and more resistant to scratches and chipping than prelaminate (melamine). I used melamine and ended up laminating it anyway to hide all the damage done during construction (it aint easy building a cab by yourself out on an apartment balcony!

BTW, use a white grease pencil for marking. Word yo.
And try getting black melamine at a lumberyard. That's where Home Depot gets it, and you can avoid their markup by buying direct. Just call on the phone and ask HD if they STOCK black melamine. If they say no, ask if they know who does. A lot of times, they'll cough up the answer if you say you need it today (meaning they wouldn't be able to sell it to you in time anyway.) Or just call around to different lumberyards until you find it.
Also, NOTHING, in my experience will keep a circular saw from chipping melamine! I tried every blade I could find, including expensive 160-tooth finishing blades, 150-tooth carbide blades, masking tape, etc. The only thing that gave a clean edge was using a router to finish the edges after I ripped the boards with the circular. Also, be careful sanding the edges, make sure you only sand along the edges, not across them! Cross-sanding will chip as bad as anything.
Good luck!