Hi C.,
I wouldn't worry about it too much. If you decided to breastfeed him till 2 or longer nobody would really say anything, becaus ebreastfeeding is good for the kids and everybody thinks itis great, but bottles are looked at bad.
Tell me why sippy cups are better than bottles. They are not. They actually are about the same thing besides that the nipple is hard. There are enough studyies out there that say that switching to a regular glass/cup is the best thing to do.
So my daughter is still having her bottle at 17 month, she loves to drink out of a regular cup or one with a straw now too and I just let her do it at her own pace. Not every baby is ready for a sippy cup or to be weaned of brest or bottle. They need their own pace.
Not every child walks at 10-11 month like my daughter, lots of her friends started at around 12-14 months and some even between 15-18 months, but that was no problem, that was developmental. But it is the same with sippy cups. Give him time. They just make easier "fun" about it than walking, it is tabu to say he/shee is not walking yet? But a lot easier to say he is not taking the sippy yet?
Give him time, he will take it when he is ready and up to 2 I think it is no problem.
By the way, if they tell you it is better for the teeth. thatr is wrong too. That is a common believe in the Us and not true. The both have nipple style attachments and deliver the drink right to the same spot. Sucking ont hem is very similar too.
Just clean his teeth regular and that you should with sippies too.
T..