Grounding = being in the present moment, being in your body and feeling connected to earth. It often feels like your relaxed in mind and body and feel the heavyness of your body, feet on the ground. It is a state of being regal, like a gorilla.
Centered = feeling calm and being aware of your emotions and body sensations without being too reactive about it.
Being centered is a by product of being grounded.
For you to develop this.you have to gain self awareness. When you speak of losing connection to yourself it usually means you are so much in your head and so immersed in what is going on outside of yourself that you lose self awareness. Losing self awareness and being outside yourself comes from tension patterns you hold in your head and body.
Taking up mindful meditation, meaning finding practice to gain self awareness and insight in what your body and mind do that is causing you to take these tensing up patterns can be a long journey.
My suggestion: make free time to do meditation and do gardening, martial arts, dancing(lots of cute feminine girls). It will help to ground you, be more in your body.
As for subs any sub that would help with developing self awareness, like RoM stacked with something that also helps your social goals.