You will be dependent(at the mercy) on everyone: employees, future customers, or other vendors; when you are tiny(started recently) your startup. It’s how the world works: make best from the most vulnerable.
On the positive side, as a first-time founder: this is the best time of your companies journey to identify allies, friends, and long-time believers. When the ship is turbulent, about to sink: rats are the first to jump in the ocean.
As a leader, you have to evaluate the bottlenecks and work towards eliminating them. Sometimes it can arise due to expectation mismatch, while others for some other reasons. You have to understand you are resource-constrained and work towards feature requests which pay. What matters most is: delighting the initial set of believers, customers. It is about being focused, which should be the default virtue.