Sounds like you have a 3rd option............

Without becoming angry or argumentitive, speak to the boss and present your case much as you have done here. Break it down to the fact that for your work load and resposibilities, a gross hourly of $13.00 is not nearly what your performance should allow. Maybe "leak" out that sometimes you feel you're doing the work of TWO people! (which sounds like you might be, as far as responsibities go)

......knowing that replacing you with an unknown, while at the same time INCREASING his workload to fill in any weaknesses in a new hire,......just might get you what you want. $3 to $5 more/hour seems fair to me, with annual reviews and any raise based on continued responsibilities being performed and reflecting growth in the business. (and that nasty "inflation" thingy!)

Nobody wants to feel under-compensated,.....been there, done that. One of my last and best jobs doing jewelry repair was at a mall where the owner and i agreed to split the repair work reciepts for what i produced.

I worked HARD also,....usually too much actually, but NEVER felt undercompensated. Often 65-70 hour weeks generated $1500 pay weeks, although i was basically an independent contractor and responsible for my own taxes and SS payments.

I did the only "in house" jewelry repair and diamond setting in the mall, we even had a Sears contract for a few years before someone new to management there decided they were supporting a competitor of sorts.

What he forgot was that i would OFTEN size an engagement ring bought at Sears while the customer waited, as couples want to show family and friends their new status RIGHT AWAY!

I even went down 2X a week to pick up their new repairs, and drop off the completed ones,.....and ALL at a discount to our normal pricing. (but we got volume that way) I don't think Sears was being smart in changing the arrangement, not as far as getting the best customer service for their customers. But i still had 80-100 jobs piled up constantly, no matter how long i worked.

.....i did quality work,....andeevn now the store i worked at misses me. The jeweler they use now (not in house) does crappy work and customers complain a lot,.....but they can't find another "me".

A few weeks before christmas i put in some 100 hour weeks,....now THAT's working! (but was fairly conpensated!) Keep in mind no paid holidays or vacation time with an arrangement like that,.....you got paid for what you produced! I kept a weekly log of job number performed and charges to customer. We deducted any part cost before the split,...also.

Worked 8 years there and moved on. At almost 47 then i wanted more of 'Me" time, so worked another 5 years at a 9:00 to 5:00 job where money was way less, but i felt i was living a bit. Still an average 46 hr week though, but compared to 7 day weeks at the mall with just 3 days off a year it was much better. (mall closed on christmas, easter, and thanksgiving)

......working all those long and hard years game me the means to retire a few years ago,....at just 53.

......anyway,...lots more options for you than you may realize,....as you seem like a hard worker also.