Finger holes (hopefully) explained....
Finger hole size on clarinets can vary considerably - not in absolute terms, but just enough that those with slim fingers can encounter troubles with coverage unless they are very well trained (which is something that new players are not, by definition). That's why I always insisted that the young girls who studied under me (which was not as sexist as it sounds when written out) always started out with the smaller tone holes of a Vito clarinet. Once a player is more experienced (and has developed a better concept of just where their fingers should be held and placed), a move to an intermediate or professional clarinet with larger holes is in order.
The holes on horns are, like everything else, a compromise. A larger tone hole allows the sound issuing from it to better propagate when the instrument is played. However, there is an upward limit to how large a hole can be when "stopped" by a human finger bone.
Various solutions have been arrived at by the different makers, and for the most part they work pretty well for most players. However, the further "down" the instrument the holes get (in general terms), the larger the opening needs to be to "work properly". That's why that problematic sixth hole from the top is so much larger than the first one, and here the size of your slender right hand ring finger comes into play.
Problems with tone hole coverage translate out (in the real world) into squeaking (as a hole is not fully covered acts as a sort of unintentional register key, and allows the instrument to sound a different set of vibrations (the squeak) instead of a tuned note). And squeaking results in frustration, often to the point of abandoning the instrument altogether.
The next larger clarinet in band terms to your Bb soprano instrument is the Eb alto clarinet, which sort of resembles a large tobacco pipe. In the dark days of the past, some of these were manufactured with the same open tone holes and rings (which, looking like eyeglasses from the old days, were called Brille, or "eyeglasses" in German) as on the much smaller soprano horn. The probably theory here was that the alto, with a tone quality that has been described as "vapid" by those who ought to know, would benefit from the greater projection that non-plateau keywork offers.
However, open holes on alto clarinets are (relatively speaking) of monumental size, and it takes perfect finger placement (and hefty hands) to cover them well. Yet, in many band situations, the alto clarinets are given to weaker players (who have trouble with the soprano finger coverage in the first place), the prevalent thinking being that the easy alto parts will cause them less anxiety and stress. In actuality, putting a weak soprano player on an open-holed alto is a recipe for disaster, as such players are often young girls with slender fingers.
Along about 1950 or so, the manufacturers of so-called "Boehm" clarinets wised up, and started producing nothing but plateau keywork on alto clarinets. (Bass clarinets, the next size up, already had all plateau keywork, as even the first finger hole on such an instrument is too large to stop with a human finger.) Mind you, it didn't improve the alto clarinet all that much, but at least their hearts were in the right place.
There is another clarinet between the sopranos and the alto, the seldom seen (outside of orchestra circles) basset horn pitched in F.† It is (in practical terms) just a large soprano clarinet, especially in terms of its keywork. As it is larger, the finger holes and their rings are also proportionately larger.
And, many soprano clarinet players encounter significant difficulties when they make the infrequent move over to the basset horn (usually to play true classical music by Mozart and Beethoven) and suddenly have to deal with the larger finger holes. Whenever I had to do this (using an old Selmer basset horn owned by Washington University (Saint Louis), it took me a good week of frequent practice before I was hitting the finger holes just so.
So, cheer up - it could be much worse...
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† There are actually two other "common" clarinets between yours and the alto in Eb:
One is the A soprano, frequently seen in orchestral work. (Symphonic orchestra clarinetists almost always own both a Bb and and A soprano.) On that instrument, both the finger holes and the distance between them are significantly larger than on the Bb soprano. This fact of life presents problems for some when making the switch.
The second instrument is the rarely seen (in the United States and Western Europe) clarinet in G. Used almost exclusively for ethnic Turkish and Bulgarian music, the holes and the finger spacing on these instruments are (compared to your Bb soprano) monumental. To make matters even worse, the keywork on such instruments is always of the so-called "simple" type, a variation on the original six-key clarinet that may incorporate some Boehm innovations like rings, but much of the horn's structure is that of open finger holes without rings or tone hole chimneys. I've never played one, and have only held one once, but I could tell just from the feel of the instrument that I was not cut out to play a clarinet in G.