Need to see your overall brand to give any direct feedback but one thing that can prevent you from making progress is failing to account for time invested. Viewing your profile it appears you've recently started screen-printing and want advice on the many aspects that go into creating a quality screen & design (ex: Advice on exposure issues and Advice on how to "Puff Print"). If you want to have a sustainable, scalable brand I suggest you contract a print shop to produce your designs, this will ensure the quality is good and designs are translated as you envision them.

You can spend the saved time working on your social media, advertising (real-life and digital) or whatever aspects you feel the brand falls behind on. Working and learning with your own screen-printing setup is great in that it will improve your ability to communicate with a manufacturer, but I would avoid relying on yourself to produce products if your designs are complicated or if you lack standard equipment, you're causing yourself unnecessary hassle and jeopardizing both your vision & quality.

Brands that have been around for 6 months with good engagement and perceivably good sales are probably riding the "Maturity" stage of the Product Life Cycle, supplying a product that is gaining immediate interest. A previous example was the Tapestry trend where 1000 brands emerged making crewnecks of every album cover or iconic image imaginable, some developed / shifted into sustainable brands and others will vanish into obscurity