K.L.
When my son was nursing (2010 and 2011) I was told by a nutritionist that I needed an additional 500 calories to provide properly, as well as a well balanced diet. That was when my son was under 6 months of age, and I am not sure if it changes to more as the child grows, and then goes down as the child starts to eat more solids.
With that said, it does not sound like you are eating enough for even yourself. You have said you will probably eat some chicken, veggies and toast. And you have already eaten almonds. That equates to one meal and 1-2 snacks (depending on how many almonds you actually ate). You should really be eating 3 meals and 1-3 snacks daily. Also, your diet does not mention any dairy or fruit, so from the information given, I would say you are not eating a well balanced diet. Nursing or not, this diet does not seem to be very healthy (although I am glad you are feeling energy form your vitamins). I would definitely give myself some more "reminders." You can still graze, but eat a little better quality throughout the day!
Your son is almost 2 years old. I am not sure what your breastfeeding plans are for the future or how long you will continue to nurse. If you plan on stopping soon, then you can probably just continue on and wean when you are ready. If you plan to nurse for the long run, I would definitely recommend going to a good nursing site like kellymom.com so you can figure out what the particular needs of your son are for his size.
Good luck and congrats on nursing for as long as you have!