Today I spend the morning with a group here at school critiquing the ten pages I sent in in December. Critiques are useful no matter how many years you have been writing. In fact copy editors critique you all the time. But it doesn't make it any less nerve wrecking- you wonder, will the reader like it? What impressions will they come away with? What can I learn? Will someone be mean just because they feel they can? :)
Welcome to the world of writing. Even published your work is critiqued every day- the evidence of that is in your reviews. It doesn't make it any less nerve wrecking. Have a great day!