How to know that you have anxiety?

excuse me for my poor language , English is not my native one

The first time I heard one describe what anxiety looks like she said that it feels like you are trapped in a box made of glass and you feel that everybody is staring at you judging you and just focusing on everything you do .

Some days after I just kept thinking about it and I was so related to it that I finally understood why i was so nervous doing any thing around people , whether i loved it or not it was always so much pressure .

put i still do not know , is this realy anxiety ?