I’m exhausted and feel like I’ve lost myself.

I have a 14 month old and am 4 months pregnant with my second. Earlier this week I was on a walk with my husband and just started crying because I am just always so tired and feel like a shell of a human most days. I’m mostly sahm and work one day a week. I loveee my son so much but I’m just tired and don’t really have any friends. The close friends I have live in different states. I feel pretty isolated and it’s so much effort to get out of the house. The town that has the activities I want to take my son to is 15 minutes away but we can’t afford to live there. I think I know the things that would make me feel like a person and be good mentally physically but where do I get the energy to do those things? When my son naps I just lay on the couch. Money is tight since we are mostly on one income. I just feel kinda lost and I’m giving my absolute all to my son and pouring from an empty cup that I don’t know how to fill with no energy and no time. Does anyone else feel like this?