Number of posts
789 posts - most probably since the opening of the account in 2013.
Keep only the last 3-month activity and archive the other posts. Who will ever scroll down to know what you did two years ago?
Moreover, the more choice and perhaps redundant images, the more difficult it becomes to like. People like by impulse in less than 3 sec. Keep max 9 to 12 images.
Instagram is becoming like the Twitter in images, the viewers are interested in what happens now. And, today, the "now" is even shorter.
Post regularly but do not spam your followers. An IG post got a lifespan of 2.5-day max. See Tips about the posting planning (How cool is Instagram?).
Post on different days, every two days, to see when your followers are online. Most people are between 19.00-21.00, every day of the week.