There is a very simple way to tell if your stitches are too loose.
If you are able to grab the string going across the track in your stitching and pull UP at ALL, that means that your stitches are too loose.
It is not best practice to pull stitches on a client.
If you are unsure if your stitching is tight enough then you want to stitch a row on a mannequin head and use that instead.
Once you are used to how your stitches SHOULD look and feel, that will make it much easier for you to find a rhythm with a client.