It may have to do with how you are formatting the lines and spacing your text and photos. (And it could be Blogger just being in one of its cranky moods.)What I do that has worked so far is type a line of text and then upload my photos and place them into the post.Also it could be the browser you are using--and they can look different in another browser once posted.
I type all my text and then add an extra return where I want my photo, then upload that photo. Then i go to the next place that I want to put a photo and repeat.
I have been having problem with blogger and photo's for that last 7 days. I actually gave up and my post tomorrow will be without the photo's Glad to know it isn't just me being technology challenged.Have a good day!