I have few questions.
Do you receive regular comments at your blog?
Do you see good returning visitors?
If answer is yes, Congrats! Your site has good retention capacity. You should start a personal space to connect with your audience.
It’s not neccessary to spend on fancy forum software, it can be anything which is easily accessible to your audience.
- Telegram channel
- Facebook Group
I would recommend choosing a platform that has (a) proper notification system and (b) UI.
I would not recommend using any WordPress Forum plugin, mostly are slow and outdated in design. You would be on mercy of developer to fix its bug. So, choose one carefully that has stability.
If your goal is ranking, Focus on running WordPress Blog instead. Don’t aim ranking with forum software because it often having so many thin pages with almost no SEO features.
Let’s Forum do what is suppose to do (connecting with audience) instead targeting keywords and chasing ranking.
All the best!