11 years old cat can be spayed?

Hi, I've had my female indoor cat for 11 years now and I've been wanting to spay her for a while but my family has always been against it especially since she is an indoor cat and is scared to go outside.

When she was younger she used to go in intense heat but as she became older the symptoms seemed to ease, however in the last 4 months her heat seemed to worsen and she keeps on meowing even during the night and eats and drink a lot.

Should I spay her or would it be dangerous since she is 11 years old and small (she is a common cat but her body is lean and has a shorter body than the average female cat)?