Interesting points ladies! Thanks for the replies. In return, I've done some digging and taken some pictures and here's what I've come up with:
First thing I found was that Laura Ashley does indeed have insects (exactly like the butterflies/moths on my dress) in her prints. Here's one print called Summer Palace that you can still buy. The link to the Laura Ashley website where you can find it is here:
https://www.lauraashleyusa.com/products/summer-palace-duck-egg-wallpaper
Here is a picture of the print:
And also in a 70's print called "Shepard's Purse." This photo is taken from the Laura Ashley (they themselves) Pinterest page
https://www.pinterest.com/pin/194077065164865148/:
Also there is the Floribunda print that has insects. (ACTUALLY, I JUST REALIZED-FLORIBUNDA IS THE PRINT OF THE CREAMY YELLOW DRESS!!) This pic also taken from the Laura Ashley Pinterest page
https://www.pinterest.com/pin/472878029595995451/:
Secondly, the style of the dress is smock like, which is exactly where LA started—with aprons and smocks. She herself wore this kind of dress as shown by this picture here which is on the cover of a Booklet for sale during the LA exhibit in Bath, England. Both the styles and the sleeves are similar to my brown dress.
Pic:
Here are some other images of that style either taken either from the Laura Ashley HQ archive in London or the Fashion Museum in Bath. In this picture, my creamy yellow dress is a shortened version of the dress on the far right (you can only see half unfortunately). From the front yoke to the Edwardian sleeves it is the same style. The dress on the far left is also very smock like.
:
Here is an 80's ad for LA with a smock dress also taken from the LA Pinterest page (is that a very young Kate Moss?):
I believe the look is just smock like and not maternity (although a pregnant woman would certainly be comfortable!)
Lastly, here are the pics of the labels. As you can see, the ones underneath just show the sizes as also shown on the front. They are sewn together well with the weathering of the labels being exactly the same color. I'm not sure why they were sewn together like this, the add on tape "100 Cotton" label on the front of the brown dress is also interesting, but I do believe they are the original labels. My one thought (having worked in fashion) is that these were maybe samples.
Phew! I learned more about Laura Ashley then I ever thought I would need to know. I love to dig into fashion research. Time flies.
I'm going with the early 1970's.

Nina