Undecided about gaining weight

Hi, I’m Alexandra, since I was little I have had thoughts about gaining weight but I have never tried to actually do it. The last year I have been thinking more about going for it but it seems I only want to gain when I’m in the mood and the rest of the time I feel weird to have these thoughts and love my slim, athletic body and don’t want any more fat. I wouldn’t gain to be fat but my definitely chubby, enough to fulfill some of my fantasies of having a slightly jiggly belly, muffin top and thighs that rub. What should I do? I’d feel a bit weird to give into these fantasies but at times I find myself going to buy cream from the shop and then after I’ve had it I feel proper guilty !