Since your RNA is small, you better add more ethanol (3 volumes).

If this does still give a significant loss of RNA, it might maybe help to concentrate your sample a bit before adding EtOH, NaAc, MgCl2 and glycogen. You could also replace the NaAc with 0.8M LiCl if you don't need your RNA for vitro translation or reverse transcription.

As an alternative method you could try to use spin columns with a protocol for miRNA cleanup.

Thanks!  Someone else recommended 3 volumes EtOH also. I'll see how that goes today.  I'll look into spin columns if all else fails - good to know that's an option. I also found linear polyacrylamide (LPA) may be a better carrier to save on yield as it can apparently precipitate picograms of nucleic acid - so I'm attempting that as well.

Isopropanol can indeed also be used. But I don't know if the precipitation is better.

But, to my knowledge, RNA will not dissolve in 75% ethanol in water, in fact, it can even be stored at -20 in 75% EtOH.

Are you using siliconzied/low binding tubes?  nucleic acids have a tendency to stick around the edge of tube, even when you spin down and if you resuspend, but don't add liquid to the edges, you may likely lose some that way...the low binding tubes may help with that.

Please try Isopropanol as already mentioned by Marco Kelders. It also proved to be better than Ethanol for precipitation of tiny DNA oligonucleotides.

You can try also Glycoblue - the pellet is more visible. After adding Glycoblue mix well, afer sodium acetate also, after adding ehtanol as well.  Do not dry the pellet for longer than 2 min. If you get pure RNA - you get lower absorbtion and probably this is the real RNA concentration you have. 

I usually use cold ethanol (-80°C) for the precipitation. After that I put it again in the freezer