I am in the same niche as you regarding design. But I rarely do a mold design, especially about injection molding because I do not master it well.
All in all, as the other said, you have just joined Fiverr this month. It takes times for your gig to get noticed by buyers. So you have some time to learn how Fiverr works, you can search and learn here in the forum some tips of improving your gigs and profile. Keep advices from successful sellers as they have more experiences and have more knowledge about Fiverr. Moreover, if you are used to working for 12hours, in freelancing you might work for 12 hours/day too. Even more sometimes. But it's up to you to give value to your working time.
Good luck.