It may have happened many times that after editing an image you immediately hit done button without turning on the share settings. Well, you are not just the only one who has done it. We all have been through this in the initial stages. Luckily, there is a way you can still share an Instagram photo that you have already uploaded.
1. Launch the Instagram application
2. Go to your profile page and navigate to the photo that you want to share on on your social networks.
3. Tap 3 horizontal dots "..." located just below the photo and then select 'Share Photo'.
4. Now here you'll see a set of icons corresponding to various services. select the network where you want to share your photo.
5. In case you have not yet connected your social network accounts with Instagram, you'll be prompted to log in. (The icon will be highlighted in blue once you've connected.)
6. After connecting the account, tap Share in the upper-right corner.
This is how you share an Instagram photo that you've already uploaded.