Weak growth can come from two very different places. The right people may never hear about your product, or they may try it and find too little value to return. Sometimes both are true.
Start with the people who arrived.
Can you describe who they are, what brought them in and what they did next? If a well-matched visitor consistently reaches value and comes back, your reach or message may deserve a closer look. If those visitors also leave quickly, investigate the product experience and the problem you promise to solve.
Don't diagnose by traffic volume alone.
More traffic cannot tell you whether the offer is right for the people it attracts. Look for a small set of appropriately matched users and observe their path from first impression through a useful outcome and, where relevant, a return visit.
Make the next experiment specific.
Write a hypothesis about one audience, one promise and one observable action. Test the message and the product journey separately enough that you can learn which change mattered.