Advice please!!

I only stopped taking birth control as of mon 13th jul(after taking it for 6years) as that was the day I was due to start a "new packet" as my bleed finished the day before (Sunday) as me and my SO decided we want to try and start a family. The last two days I've had a lot of lower back pain and feeling sick also having up and down mood swings along with going to the loo a lot for a wee! More often than before anyway. Is it possible or too soon for me to conceive or not?