I think you have the hang of the 25 needing to fit into the range of numbers on the inner tube. These numbers refer to millimetres, the width of the tyre, and tubes can be stretched within reason to suit a few different sizes of tyre.
You're right that the 700 x 35-38 tube is way too big. If you chose that one, it would be unnecessarily heavy and the bagginess of the tube would make it more susceptible to getting pinched when the tyre gets mounted. Putting a hole in the replacement tube is never fun.
Now the 700 x 18-23 tube is a marginal case. This time, the tube will be stretching up to and just beyond the size it is designed for, by 2 mm. There is a difference of opinion on whether this is a problem or not. There was even a semi-recent question on this site about whether a tube should be used at the low or the top end of its range and lets just say there are arguments for either case (cyclists can rarely agree on anything). I would certainly use one of these if I didn't have an alternative but I would prefer to have an 18-25 tube so that it wouldn't even need thinking about.
By using an 18-23 or 18-25, when you put a little air in to install the tube, it takes its size and shape without any bagginess and stays out of the way a little better when you mount the tyre.
So yes, it would be best if there was a 25 in the size range of the tube and 700 x 18-25 tubes do exist quite readily if you can track down a shop with them in stock. 18-28 would also be just fine of course.
TL;DR I think you're on the right path, just facing a bit of doubt because you haven't found them in stock yet. That said, 25 mm tyres are very common on road bikes so I’d expect most bike shops to stock a compatible tube, keep looking and don’t be afraid to ask shop staff to direct you or dig one out from the stock room.