What is going wrong with my knitting?

Try this

It may be how tight you pull the stitches as you go along. You may be getting more comfortable with the stitching as you go along and so the stitches become looser. This is just a skill that comes with experience.

I get to the last stitch (slip knot) and it just doesn’t work

I have much better luck when I cast on with two needles, whenever I try to cast on with one I have the same problem you are having. Using two needles sets the gage perfectly and keeps that from happening. Here is a video showing how it is done (it is perfect that it is a British woman doing the explaining because it was my British aunt who taught me to cast on this way). Once you get the hang of it it is as easy as using one needle.

You are not yet in your late sixties, I would assume.

@veganpeanutbutter What is the point you are trying to make? I have been knitting ever since I was 16, a half century ago and most of the people in my classes are in their early 20’s.

How does your answer help?

@YARNLADY: I think it’s supposed to be a joke, it’s just a really crappy one, right? lol

@La_chica_gomela Maybe she meant we just get better with age.

@La_chica_gomela Indeed.
More often than not, I am joking.

Let it be known that I am seventeen and I knit, along with many of my other friends. I was simply “cracking a joke.” My apologies.

@veganpeanutbutter fair enough

@veganpeanutbutter: ditto what @yarnlady said

Maybe you are not knitting tight enough. Or maybe it is your long tail cast on I’m guessing that’s what you did I like to knit on or use two needles, however you want to term it. It depends on what kind of a project I’m making as to the cast on I use. If you’ve not been knitting too long, just keep after it and you will get better. Good luck!

If you use the loop-over-the-thumb method to cast on, that’s common. Just don’t pull things too tight when you knit the first row.

Alternately, try a different cast-on method. There are dozens.