At 2, my DD2 was not talking - except some essential words like NO, Mamma, Daddy, Bok (for a drink).
At 2 years and 10 months, she had not advanced much beyond this, single words only to convey what she wanted and would talk only to immediate, familiar family members.
Our public health nurse was concerned initially but I was completely confident in her ability to hear and understand instructions and DD's single words were quite clear. She didn't speak the whole time the nurse was in our home. The nurse moved on from age 2 in her picture book to age 4, then 6, then 8 and DD was able to point to any of the items or activities described by the nurse though she failed to distinguish colours - only for the nurse though, she knew them quite well..
At 2 years and 11 months, she suddenly gave a speech from the back of the card, not just a sentence, a whole string of them added together containing amongst them a sentence which on paper would have included a !, one with a ? and a couple admonishing her elder sister for failing to eat all of her lunch on her first day of school as she would be hungry and the fruit was good for her. There has been no shutting her up since.
At 3 years and 6 months DD2 was fluently reading DD1's school books, she cracked the code whilst sitting on my lap.
Here's the thing to give you hope - by age 7/8 ALL of the children in DD2's class could read as well as, or almost as fluently as her.
Children are all different and develop different skills at their own pace. Enjoy this precious time with your DS and give him as much support and encouragement as you can. Don't compare him with his cousin, at 2 a six-month age gap is huge and girls are different to boys anyway. Let him run wild in your garden and let him enjoy being a toddler.