Tiny ecuadorian hasn't molted in over 2 months?

We've had my little guy for just under 3 months now. He's an ecuadorian hermit crab and his legs span around 7/8 of an inch. He's eating well, he's quite active, he's very fast, and he goes to his pools frequently. Our humidity for his tank is at a consistent 85-93% and his temperature is always around 75-80⁰, and the sand is sandcastle consistency all the way through. He is a strong climber and seems quite healthy. We feed him a proper food mix we got off Etsy which has all the main food types hermit crabs need, and he seems to enjoy it. In the first week we got him, he molted. He took about a week and a half to emerge from the sand. He regrew part of his limb that was missing when we adopted him as well. The issue is that he hasn't molted in over 2 and a half months, and I'm beginning to get very worried. We looked everywhere for specifics in timeline for molts, but our research was unconclusive. Some sources said ecuadorians are different in frequency for molting, some sources say all crabs molt at different frequencies, some said they always molt the same frequency regardless of size (which i can say with absolute certainty is false). His sister who we got a few months before passed a few weeks ago from what we believe is PPDS during her second molt. We had another crab we got shortly after her from the same petsmart (which we now realize they treat the crabs horribly) and he passed before his first molt, but we could tell she was lonely, looking for her brother in his usual spot, so we decided we had to get her a sibling, the ecuadorian we now have. we got him from a different pet store with much better husbandry setup for them. My husband and I are having a hard time. We want to get him another sibling but don't want to introduce them if he's just about to molt as we think it might add to his stress, but we're also worried that he might be lonely and that's why he's not molting? What should we do? And is he going to be okay? I love him so much. I just don't want to lose my special boy. We've lost two and we're certain it's because of the horrible conditions they were kept in at petsmart, and I can't handle losing a third. Attached is a picture of him looking very handsome after his first molt because he is my special guy.

We've had my little guy for just under 3 months now. He's an ecuadorian hermit crab and his legs span around 7/8 of an inch. He's eating well, he's quite active, he's very fast, and he goes to his pools frequently. Our humidity for his tank is at a consistent 85-93% and his temperature is always around 75-80⁰, and the sand is sandcastle consistency all the way through. He is a strong climber and seems quite healthy. We feed him a proper food mix we got off Etsy which has all the main food types hermit crabs need, and he seems to enjoy it. In the first week we got him, he molted. He took about a week and a half to emerge from the sand. He regrew part of his limb that was missing when we adopted him as well. The issue is that he hasn't molted in over 2 and a half months, and I'm beginning to get very worried. We looked everywhere for specifics in timeline for molts, but our research was unconclusive. Some sources said ecuadorians are different in frequency for molting, some sources say all crabs molt at different frequencies, some said they always molt the same frequency regardless of size (which i can say with absolute certainty is false). His sister who we got a few months before passed a few weeks ago from what we believe is PPDS during her second molt. We had another crab we got shortly after her from the same petsmart (which we now realize they treat the crabs horribly) and he passed before his first molt, but we could tell she was lonely, looking for her brother in his usual spot, so we decided we had to get her a sibling, the ecuadorian we now have. we got him from a different pet store with much better husbandry setup for them. My husband and I are having a hard time. We want to get him another sibling but don't want to introduce them if he's just about to molt as we think it might add to his stress, but we're also worried that he might be lonely and that's why he's not molting? What should we do? And is he going to be okay? I love him so much. I just don't want to lose my special boy. We've lost two and we're certain it's because of the horrible conditions they were kept in at petsmart, and I can't handle losing a third. Attached is a picture of him looking very handsome after his first molt because he is my special guy.