Building a SAAS product - feeling nervous because it is a David vs Goliath

I am building it in the email marketing space. basically its a tool that uses Amazon SES to send emails super cheap compared to Mailchimp et al. I am trying to distinguish by having a really intuitive user experience. Worked on it obsessively for more than 2 years now.

I feel overwhelmed that I may not have what it takes to compete with the big guys like Mailchimp and Sendgrid. Mine is called SendNet.io by the way

I have no ad budget at all. Can anyone on IH give me pointers as to how I can market this myself?