Why there will be a drastic drop in website visitors count?

I have a landing page for my startup. Very simple page. I don't do any web site marketing, but I am very active in Instagram (adding posts, commenting and also have 8k followers).

I noticed thro' Google Analytics on an average there were around 400 visitors to my website each month for the last 6 months. However, for the last two months the number went down to 75. I checked my GA and i don't see anything alarming.

Also, i am a developer. I am not an expert in marketing/SEO. Looking for your thoughts.

Thanks.