My Baby Boys growing to fast!!!

So my son is almost 5 months old and it makes me sad. He is growing to fast he rolls over all the time, I started feeding him cereal and fruits and vegtables about 3 weeks ago and hes just not to sure of it yet, I he likes it or not. But hes the sweetest thing on earth and it makes me so sad to know that he is the last baby I will ever have!!! I'm like just stay this little forever!!!