Downsizing an image

Hi there. I'd really appreciate some help!

From reading some of the other threads about downsizing images, I understand that you can expect to lose quality when reducing the image size quite drastically. I'm going down to 7% of the original size. The result is very pixelated.

However, where I'm very confused is that I've done this before without any difficulty.  I've previously used the exact same photo format from the same camera, reduced to the same sizes in photoshop, with no pixelation. The only thing that I can think of that has changed in the meantime is that I had to upgrade my photoshop from a very old version.

I've tried resizing them as JPEGs before importing, ticking and unticking the 'resampling' button when resizing, importing them directly from the phone that took the photos to photoshop, experimented with 'bicubic' and 'bicubic sharp' when transforming.... I'm afraid this is as far as my (rather limited) photoshop ability and knowledge goes.

Any ideas for what I can try?!