Hello.
The technique you tried was WILD, entering a lucid dream directly from your waking state. There is an another technique called DILD, becoming aware that you are dreaming during a dream. DILD is considered to be easier. If you try to WILD, you will probably experience SP (sleep paralysis) and HH (hypnagogic hallucinations). Feeling weight on your chest is a common sign that accompanies SP. You should be happy you experienced SP on your first try, it is a big step towards succeeding in WILD. There is nothing to be afraid of. However if you dislike it, you can try DILD instead.