I believe you are exhausted.
Does the child's father help?
Do you have family or friends that can help?
By help, I mean perhaps caring for your toddler for a 2-3 hours and let you do what you want, ie: sleep, take a bath, go for a walk, be with friends.
That alone can help dramatically especially if you can arrange it for 1 or 2 times per week.
What is your diet like? Is there anyway to ensure that you are eating good energizing foods? Sugar will sap your body and over time will do dammage to your energy levels.
Eats lots of raw fruits and veggies, leafy greens, nuts and seeds and whole grains. Do your best to not eat processed foods. Organic is best, if it is available to you.
But rest assured it is normal to lose your patience with a toddler. Dealing with a 2-3 yr old is one of the most stressful times for mothers. If ever you feel like you are going to lose your temper, make sure your son is safe and playing happily (nothing around that would be dangerous to him) and go to a quieter part of your home, perhaps the bathroom if necessary. And, close your eyes, take some deep breaths, and remind yourself of your blessings in your life.
If you feel extreme - call a friend/relative and just explain that you really need some time, and ask if they could help out.
YOU ARE NORMAL - almost all mothers feel this way at one time or another.