Wow @Bunniekins that's a pretty good piece of knitting for a beginner! No, really. Your tension seems to be quite consistent, and that's one of the hardest things to get, so well done there. I' not seeing any dropped stitches - you get ladders when knitting stitches are dropped.
Okay, so you either decreased or increased, amazingly evenly I must say! Which is the beginning end, the narrow or the wider? I can't tell cos the image won't embiggen clearly enough for me to 'read' the stitches.
To combat either increasing or decreasing when you don't want to, know the number of stitches you started with and take a moment before beginnig the next row to count the stitches to be sure you have the same number. If you have more or less, check where you've added by looping through a part of the yarn the is not a stitch on the needle itself, or if you've knitted two stitches together.
both are easily done and even long term knitters will do it, as well as drop stitches from time to time. If you aren't sure which is the ending and beginning stitch, put a marker, perhaps a piece of different coloured yarn , a bread tag, a paper clip, or if you have them stitchmarkers through it. Keep taking it up as you do each row until you get familiar with how the end stitch looks from both sides of the work.
Tips for an easier undo and rerolling of yarn. Undo in bits, roll, the undo more, so you don't end up with a tanlgled mess.
Use a toilet roll insert, make sure there are no 'catchy bits on the outside', carefully snip a wee angled notch in one side to hold the end of the yarn, put the end inside the hollow. Wrap the yarn around the outside of the tube, spreading the yarn evenly-ish along and back as you wrap.
When done, you can slip the yarn out of the little notch that whas holding it, and carefully pull the tube out of the inside of the ball of yarn, and use that end to work from. This process makes a centre pull ball of yarn which is much easier to use.
Larger straight sided tablet bottles (ones with shoulders not so good) can also be used to do the same, catch the end of the yarn with the lid, and roll the yarn around the bottle. When done, lift lid, remove yarn from inside, and carefully remove bottle from inside yarn ball. Again, centre pull yarn ball.
Hopefully that will help Pea. Count the stitches on each row, hon, yes tedious, but is part of the craft and makes for less undoing! 