Every child is different and they can come on rapidly in leaps and bounds, and then seem to plateau, so I wouldn't be too worried.
My daughter was given a book bag with nightly reading (mostly books without words, and then basic satpin stuff), when she was in nursery. (Attends a 3-18 school.) By reception she was confidently reading with decent spelling when writing. Any spelling errors were still correct phonetically, and her maths was decent, but she was always ahead and rated as having the reading age of an 8 year old. The classes for the week (throughout the year) were still focused on colours and numbers 1-20. I thought this was terribly basic, as my daughter knew all of that before age 2, but there were actually many children in her reception class who didn't, so I think my expectations were just wrong.
With my youngest, he has known numbers 1-10 visually since about 2, but could count things up to about 15-20 at that time. He has known letters since turning 2 as well, and his vocabulary is very advanced, but he has no interest in writing or reading, will not attempt to blend letters, and doesn't want to hold a pen, even for colouring. He is 3.5 (summer baby), at the school nursery and starts reception in September.
Both my children are so different. The eldest will show off everything that she knows. My youngest isn't inclined to at all. He just has no interest, but that doesn't mean he doesn't know things. I.e., he's not attempting to write his name, which some of his classmates are, but he knows more letters than them, so on the one hand he seems behind them, and on the other hand, ahead.
As long as you are spending time with your child to help them, without forcing the issue, they will be fine and have plenty of time to catch up/want to do it for themselves.