I think you need more time to see if the RoC cream is working for you or not. One month is too short to tell. Even stronger retinol products like Retin-A or Renova won't give you results until at least 3-6 months later.

Other products that I think can help you are the Epidermx home microdermbrasion cream and Silkia camellia oil. I don't have deep lines on the forehead, so can't speak for that. But I used to have some moderately deep pitted acne scars and they have been hugely better after using these 2 products. The site I ordered from have before and after pictures of people with great results for diminishing wrinkles on the forehead. So I think they will work for you too.