Amanda Bynes Living Sad, Isolated Life After Mental Hospital Stay

Amanda Bynes is facing a tough reality after spending weeks in a mental hospital, often feeling sad and isolated, as she works to balance her medical needs and where to go next in life ... TMZ has learned.

Sources close to Amanda tell us ... she's back living solo in her own place after her recent release from a mental hospital, but she doesn't have a lot of people in her life.

We're told Amanda hasn't been focusing on some of the passions she had before she was found roaming the streets naked in March -- like fashion design and being a nail tech.

Instead, she loses interest quickly ... though, we're told she could pick up those interests again down the road.

The good news -- our sources say Amanda is really good about attending her outpatient treatments, seeing therapists, and taking her medication.

TMZ broke the story ... she was released from a mental hospital last month, 3 weeks after she was first admitted for treatment.

While Amanda's alone these days, folks around her don't want to see her get back with her ex, Paul Michael.

Our sources say Paul wasn't there for Amanda when she was struggling, and they want to see her move on from him because they feel he's toxic to her recovery.

We're told Amanda mostly just communicates with her parents and siblings ... and actually sees her parents from time to time.

So, while she's isolated from friends, at least she's on good terms with her family.