I lady I used to go swimming lessons with said her LG had only 2 front teeth till she was nearly 2. It’s just another one of those things babies develop at their own pace
My little girl only had her two bottom ones for months and out of nowhere the top 4 have all cut within a fortnight. We know some babies them same age who have lots and lots. They all get them at different times, I wouldn’t worry at all ☺️
My little girl (13 months) has only her 2 bottoms ones & one of her tops ones. If you can see the teeth in his gums I wouldn’t be too concerned but you can always speak to the dentist about it. Some babies teeth are just slower to come in. You may find that some come through at once x