Have faith and patience A..
My step sons both were attached to their sippy cups when they came to live with me. After the settling in period I started DEtaching them.
I allowed them to drink from the sippys but they couldn't carry them around with them during the day. It was worst at bed time. They had always had them and rather than take that security away and spend nights without sleep we allowed the sippys to help them get to sleep...for a while.
During the day the sippys stayed in the kitchen. We had to put them on a wooden tv tray so they could reach them and they could come take a drink anytime they wanted. Eventually I started replacing them at various times of the day with small plastic glasses.
For a while they refused to drink from the glasses. We told them that only if they used the glasses would their sippys be on the table later.
Eventually the glasses were available 90% of the time and the sippys 10%. One day the sippys just didn't show up at all but by then they were comfortable with the glasses and didn't really care.
This process actually took a lot longer than it sounds like but gong slow was worth it. Friends who had the same issue complained of tantrums and acting out and sleepless nights after just saying "no more sippy cups" Doing it the way we did we didn't have anything like that.
Sleeping in their own bed....
If you are not currently sharing your bed with anyone else then why not see the joy in your son spending that quiet time to be close to you?
I was a single mom for 13 years. My daugher always had her own room and own bed but it didn't get used much the 1st four years. I always worked full time and by the time dinner and bath were done it was her bedtime. It was a joy to crawl into bed and read books and look at patterns in the ceiling and later to talk about "stuff" and hum songs together. It really was the only time I had with her during the week and I don't regret it. If it was occasionally inconvenient I would simply go through our normal routine and after she fell asleep I would carry her to her own bed.
Eventually SHE made the choice to spend more and more nights in her own bed. I was lucky, I guess, that her being in my bed was not a hassle for me and that eventually moving her out wasn't either. I also know that it did not harm either one of us. I can't imagine having missed those incredible together times.
My daughter is now 15. She is a very strong, independent young lady. We clash alot over normal parent/teenager things because we are both very opinionated. Sleeping with me obviously didn't cause any insecurities or attachment issues and I honestly think that we are able to work through our differences because of the bond we forged in those first years. As long as it doesn't interfere with your life at this time I believe it can only enhance it.