So the problem is not with the theme, but it’s that the iPhone (or, at least some apps on the iPhone) don’t properly read information stored in the image file as to whether or not the camera was turned sideways when the picture was taken.
When you take a picture with a digital camera, information is stored in the image file that contains data like the date and time, aperture settings, and the orientation of the camera. Most applications will read that data, and if the information shows that the camera was rotated sideways, it will automatically turn the picture so that it’s right-side up. However, the iPhone is known to ignore that information, so images will appear the way it was uploaded.
For example, here is the original image that you uploaded of your baby. As you can see, the image is rotated 90 degrees, which is how your iPhone is displaying it. It’s displaying that way because your camera or phone was turned 90 degrees when you took your image. Your desktop browser will automatically adjust the orientation and turn it to match the way your camera or phone was turned so you don’t notice that anything is wrong.
The way to fix it is to open your picture in a photo editor, and then save it oriented the correct way. Then re-upload your picture to your media library and re-insert it into your post. It should then appear OK on an iPhone.