Is it adulting or am i just a lone soul

I (F28) was never really a social person as a child , i’m very introverted and reserved. But when i’m with my close one i do talk here and there for a bit until my energy is exhausted after socializing for 2-3 hours. It’s so bad that i’m like this even with my family members. I light up like a bulb for 1-2 hours and then am completely off. As i grew up it got worse i think , i just have 1 long distance female best friend. She’s the only one i talk to,and zero other friends. I recently changed my phone number and gave it only to my that female friend and family. I live with my fiancé in a different city than my family,but i barely call anyone or get calls from them .

I hang out with no one just my fiancé, sometimes i don’t go outta my flat for days and am totally fine with it most of the time.Then i sometimes get fomo checking out my friends hanging out in instagram,but I’m also too lazy to reach out as i know it will feel too fake or desperate,not to say that me being socially awkward doesn’t help my situation, i know that i’m not that bothered living alone and like a recluse but sometimes i wonder,will this affect my relationship with others,like friends and family. I’m too lazy and not that interested in keeping touch with them just sometimes i feel fomo .

My fiancé on the other hand has a great social skill, he can literally talk to anyone and in any situation .

Someone tell me is it normal as we grow old , am i being just insecure or is it a real issue ,isolating oneself