Unless you bought them from Casa del Puro in Playa Dorada, they are most likely not Cuban..."Hecho en Cuba" on the box means nothing. Stickers mean nothing. Does the box also say "Totalmente a Mano"? Does it have a 3D hologram from Habanos S.A.? If not...you're pretty much S.O.L. (BTW, occasionally Cafe Cubano and Super Super in Sosua have genuine Cubans, usually Cohiba or Punch, at "reasonable" prices.)
If you want to confirm their authenticity, you can enter the serial number from the Warranty Seal on the box at the Habanos S.A. website:
Stamp to Verify
The good news: if they search your bags at Customs in MIA or JFK, just tell them you bought them because you got a great deal in the DR...they will shake their head, smirk at you and wave you on...they may even take them, but probably not since even they know they're not Cuban...(kidding aside, better to take the labels off and take them out of the fake box anyway).
Only Authorized "Casa Del Habano" (Habanos S.A.) distributors/resellers sell real Cubans. And there's only one in the DR. If you bought from anyone else, even if the box says "Hecho en Cuba, Totalmente a Mano" they are 100% fake....true pretty much anywhere in the world...even Cuba!
The only other way to buy real Cubans here is to buy from someone who knew what they were buying and bought them for retail (or higher) price outside of the country (i.e. Cuba, Spain, Switzerland, etc.) and is willing to sell them to you. I have gotten some that way, but no one has ever offered to sell them to me "cheap".
If you really want to take home some good Romeo y Julietas, buy a box (or a sampler) of GENUINE DOMINICAN R y J's like Reserva Real's (my favorite) or 1875's (Classic).
Better yet, if you have the opportunity to go to La Romana, you can tour the Tabacalera de Garcia factory where they are made, along with Montecristos, Trinidad, H.Upman, Don Diego and others... and buy them factory direct....and on certain days, you can even share a smoke with the Master Blender of Tabacalera de Garcia, Jose Seijas...trust me, it's worth the trip!