Thanks for sharing this. I usually don't give "advice" on this site but because you so bravely shared your experience, I will share mine.

From time to time I use a pacifier and children's coloring books. If I had more money, I'd buy sippy cups and baby clothes that fit me. I suspect everyone's "reason" (if there is one) is different.

I understood your post as saying that your guilt and longing stems from not being comfortable with indulging, but also not wanting to quit the infantalistic activities. If that's right, I think that balance will come from not feeling guilty about the infantalism. Don't be revulsed by your younger side. That's like being repulsed by a child. Be kind to yourself.

Everyone's experience is different. And I'm not sure exactly what you mean by infantilism because I think the word has so many connotations and meanings because I don't think it's fully researched and understood. Do you feel young? Is there any body dysphoria when you see your adult body but want to be seen as a baby? (Seen by who?) How often do you want to be young? etc.

What do you mean by involving your family?

If it helps you, I can share some of my own experience... I've always felt like there is space for me to regress. It is also a stress reliever, because it makes me feel more innocent / less guilty about my childhood. It also helps me be kind to myself, etc. But, I'm also a functioning adult (and want to be), and am pretty ambitious in the career department. You can be both, and in fact, I think it may be crucial to your adult self to be nurtured in this way. Your adult self feels guilty but your younger self longs to be nurtured. Does that resonate with you? Now this is my own theory, but if you give your baby self what they need, you might feel less guilty because you will be nurtured.

From my perspective, I don't think it's abnormal.

I hope this helped. I might be totally off topic, who knows.