i will not promote- struggling with sales even though demos go well

I am building software for construction and EPC companies. The product is not the main issue right now. Whenever I manage to get the right company on a demo, they usually show interest. My problem is that I am not able to generate enough such leads, and I am also struggling with follow ups and closing. I don't have much budget to hire a sales team right now. For founders who faced this early on, what did you do?