Landing page sign-up interpretation help

Hi everyone, today I will ask for help from some of the more experienced people here regarding starting up side projects.

Long story short, I have a validated SaaS idea in an existing market with some major competitors. I have created a detailed landing page with a sign up option and released it here, at indie hackers and recently on product hunt. I waited a month in total and so far I have around 55 sign-ups. A couple of days ago I created and sent out to the signed users a newsletter about which core feature to focus on the initial release of the service hoping to get some responses that would give me enough motivation to start building the whole thing.

I am a little bit lost on how I should interpret everything.
First of all how does the 55 sign-ups in a month without any advertising sound? Is it a good or a bad thing? Are they enough or should have been more?
What about the newsletter? So far I didn't have any responses. I wasn't expecting everyone to reply but I made it to be a one click submit within the email to be as less effort as possible but I still didn't have any responses. Should I worry about that and get back to the drawing board? Or start building the service and start selling an MVP the soonest possible?

Please give me some guidance I am lost.

Thank you all