1) John wanted to make fairy cakes, although he had limited ingredients. He went to the shops, where he would find good quality ingredients for his tasty cake. John bought sugar, flour, icing, eggs and chocolate sprinkles to complete his shopping spree. The day got longer; John ended up eating all of the cakes, as he was extremely bored.
2) John ran in fear, his heart sunk, trembling with extreme, agonising terror for his life. He escaped the brutal shooting, and made it to safety. As long as he was safe, he did not care who else may have been hurt.
3) John, the doctor, made me take a test. Shockingly I was clear, and the lump I found on my knee was a false alarm.
4) However, laura headed back to the flat in a hurry, which made her feel tired and worn out, so she took a long, well deserved nap on the sofa.
I feel like i have lost the plot, and don't feel confident using commas. Correct me if you spot any errors. I'm starting university so I'm improving my writing skills. I will appreciate some feedback of experienced student who are punctuation pros!