could you post a pic

Would you be prepared to give up the shower for a tub and shower? For the next five years it might be useful.You could remove the sink and shower and place the bath along that wall (with the shower fixture where it is)Hard to see space but could you fit a small sink in front of the window or next to where the shower was (again hard to tell your dimensions).....?

Any pics you can share of the space?

For the time being (and this IS only a temporary fix) try using a water based penetrating sealer on the grout. I stress water based, because solvent based sealers today are made to be "breatheable", meaning they allow moisture to transmit back and forth, while the water based sealers will repel water. You still need to address this in a more permanent manner (the glass door is a good idea, but it wouldn't hurt to remove the bathroom floor tile, waterproof the floor, and install a new tile floor), but this will help until you can afford to do what you need to do.