I have smaller hands as well and I've only been playing about a year, I will tell you what I'm doing/have done to help with that:

• For me, holding the guitar in almost a "classical position" (roughly a 45 degree position) helps a lot. It gets my wrist and palm at a better angle and helps with any pain while also giving my fingers the best possible reach. Experiment with positions to help you get your hands and the guitar as comfortable as possible to avoid wrist strain. A strap or a small cushion while sitting can also help you keep a position of choice when you play.
• I bought a guitar with a "Thin C shape" neck and that helps my playing a lot too. it allows my palm to sit a little flatter on the neck which in turns gives my fingers a little more reach, which deifnitely helps as you find your way through practicing. I can still use other guitars with a thicker neck, I have an Epiphone as well with a "50's D shape" neck, but as I learn new things to do on the guitar I almost always start something new with one of my thinner C shape neck instruments to align closer to my preferred posture before moving to another neck type.
• Part of it really is just practice and time to get used to what you should be doing while playing to avoid any wrist strain. As you practice more you'll realized what works and doesn't work for your anatomy. Definitely anything you can do to avoid what feels like strain is important as well, I got a little overzealous recently with my hurt my wrist some due to bad posture and I should have been more attentive to the position I was holding the instrument in.

I hope this helps you, best of luck on your guitar journey. It can definitely feel like a struggle sometimes, even just figuring out how to properly hold a guitar took me a while and I'm still learning what's best for my physiology. It's been a wonderful year for me of learning, I personally learn pretty slowly but I'm enjoying myself so much.

What kind of guitar do you have? There's a big difference in neck size between say, a classical guitar and an electric.

Having good form, like others have said, will go a long way. Some things about that which I didn't see mentioned are: try to keep your thumb centered on the back of the neck and get the guitar in a position so that you can move your elbow outward, almost to the point that your hand is parallel to the fretboard. This will keep strain off your wrist and let your fingers stretch more easily. Another thing is, if you're playing standing up, it'll be much easier to play if your strap is short and the guitar is high. It might not look as cool, but you'll see some real technical metal players do this because it really does help.

In my opinion this sounds like normal discomfort when starting to learn.

I've found some good hand stretching exercises on YouTube, I'd suggest to stretch/massage your hands/wrist/fingers a couple times a day and really take your time and use good form when practicing. https://youtu.be/TSrfB7JIzxY?si=ZN6NSRwNqWqNRNC4

Justin, from Justin guitar, (definitely check him out if you haven't already) recently did a series of videos where he taught himself to play left handed. One of his main take aways that stood out to him was the pain you go through when first learning. So don't be discouraged it's a normal part of learning, just make sure your using the best form you can manage.

Be kind to yourself and remember this is a lifetime journey, not a sprint to a finish line. Practice at least a little everyday and focus on building a solid foundation that you can expand on the rest of your life!

Cheers and good luck!

I believe Fender Mustangs have a 24 inch scale, which might make things easier

I'm having the same issue, kinda, when playing bass. The fingers are long enough, but at 50+ the joints aren't that flexible anymore. I found the tips from bassbuzz on youtube useful, especialy on the fretting techniques.

Biggest improvements here were a correct setup of the bass (still need to setup the frankenfender), correct position of the bass/guitar and correct position of the hand/fingers while fretting. Some microshifting helps me a lot, as the pinky is my main challenge. (Not strong enough for pushing down the snares)

Try to focus on having a good form. Maybe research how to correctly hold your hands. Strain on the wrist is definitely not good or nomal. Try t hold it a natural as possible.

Bigger hands make it easier to play notes far apart. But as someone with small hands aswell it is not impossible by anymeans. You definitely have to improvise when some tabs expect you to play notes 4 frets apart but it should not come with hurting wrists.

Try to get feel how you can hold your hand naturally focus on playing easier sheets without straining your wrist.

I also have pretty small hands. It gets easier when you have the right thumb position (even for easy chords like D, to make chord changes faster) and build up some strength and dexterity (exercises in the link below).

This is really good read: https://guitaristnextdoor.com/how-to-play-guitar-with-small-hands/

It also goes into gear stuff (scale length, thin and narrow neck, low action, lighter string guage, etc). Don't know what you have, but I would definitely recommend starting with an electric instead of an acoustic, unless you really only want to play acoustic or don't want to pay for an electric. It's a lot easier if you don't have naturally strong hands imo

It's not mentioned in the article, and you're in early days, but when you get into bar chords I recommend "strength training" on the guitar. Trying to hold the Fm chord (on the first fret) as long as you can, several times, with rests in between. But of course be careful, don't hurt yourself