I'm almost 30 y.o.- do I need to just grow up?

I'm 28 y.o., with no kids, no pets, no job/ career & was a house wife until a few weeks ago. I haven't worked a really job for like 5 years now. With this being said, I love to spend time with my sister's kids & watch SpongeBob SquarePants, Cars & Scooby Doo. I find when there is nothing on t.v., I'll watch those shows. I have collected postcards & anything that has to do with alligators for several years. Looking back on my life now, I see a pathetic existance & a waste of life. I feel like I'm so immature & childish! Should I just suck it up & act like an adult? I just feel so lost.