Seems like you're headed in the right direction, especially with the webinars and the guest blogging - these are a great way to increase the interest to your service.

Also, 900 subscribers by May sounds totally realistic.

However, the website definitely needs a lot of work. It looks like a general blog, nothing too professional to convey trust and authority. No additional pages for your services, it's hard to get in touch with you, the only lead form is the Hello Bar on the top (that is a bit too large).

The landing page and the exit intent popup are also really bad - you'll have to work on the design aspects or use plugins such as OptinMonster for optins and Unbounce/LeadPages for landing pages.

No related posts, no way to convince a user to stay after a post is done.

The list is long, I can share a few other things as well and help you with the design concept and measuring your leads if you're interested.