I find it very ironic to (finally) see your message on the very anniversary of my own father's passing from cancer, 12 years ago today. This was also his birthday, no less, and on that morning, I found he was gone when I went into his bedroom to say "Happy Birthday."
Needless to say I know where you're at in your healing process....hang in there....because the darkest light is just before dawn. Knitting is a great way to do something creative and can help you reflect or think about new things to come and a better future.
What the other ladies have posted here is very much the case and each has provided you excellent suggestions from their own experience. You will probably knit tighter until you have some time and experience with tension and "feel" for each yarn you work with. As you perfect whatever technique's you've learned to knit with, this will also be a factor. Try switching to a different style and see how very loose all the new method stitches become....at least for a little while, until you become accustomed to the new method.
Even after about 7 or 8 years of knitting, I still find myself knitting near the tips of my needles...mainly because of my technique. Until I saw Amy's video, I never realized it played a part in why the stitches were so tight. I'm alright with it, because I know I tend to be a tight knitter and I know how to adjust things along the way these days....because I developed a sense of tension and feel through experience.
While you develop yours, you might want to stop after each row and gently slide the group of top loops of your needles back and forth across the needle a few times. You might even want to hold the end of your needle and twirl the end around a few times (like how you'd wind a watch knob), to be sure you've "unstuck" the loops while you do the sliding.
Then with your thumb on the side facing you and your pointer finger placed over the working loop and needle (in other words, on the opposite side from where your thumb is) gently pull down slightly on the loops. Make sure you're gently tugging on the bottom "joiner" part. You'll see your working loop become slightly larger.
These two things together will help stretch your work slightly and give you back whatever "ease" is available in your work. Caution, don't pull down too tightly...and you should expect to see a slightly larger stitch for the first few rows, compared to the existing, really tight work.
Give it a try and if you're like me, you'll learn a bit more about overall tension control and give yourself a better idea of how to adjust your tension for the next row and future rows.....instead of having to suffer, fight and pull your way through them.
Keep workin' at it, hang in there and Good Luck!