The female could stand a bit more size on her, a bit closer to 250 grams but since they are together it's likely too late to worry about that now. Just make sure there's loads of food in there for her to build on some size prior to the litter being born. You should plan to remove the male before she gives birth as he'll mate her almost immediately after she delivers the litter. Some females won't allow the male to do this but since she's a small female on her first litter, I personally wouldn't chance it.

Pick up a used 10 gallon tank and you can put her in that when she appears pear shaped indicating she's pregnant.

What are you feeding them and what sort of bedding is that?

You might want to grab some wire and make a protector for that water bottle or you can take tin snips and cut the bottom out of a pop can and slip it over. Darn water bottles are expensive enough and the little boogerheads will chew a hole in one if they can.