Do you respond to Instagram comments? If you don't, you should definitely start, it is 'social' media after all.
By engaging with your followers via your own content it tells Instagram that your account is active and responsive, which means your content will be shown to more of your followers.
You should aim to trigger a conversation with your followers, post insightful responses and offer recommendations.
Give this a try over the next few days and notice if you get more engagement on any further content you post.
Combined with posting great content consistently, you should see your following and engagement increase.