Well, I guess I'm going to sound like a broken record, but I also agree with the other two responses...keep on breastfeeding. I breastfed my daughter until she was 2 years old.
If you don't have another major conflict, then I'd keep breastfeeding him. Every month that he continues to receive not only the unmatched nutrition of the breastmilk but also the unmatched nurturing of the breastfeeding time, he will develop in ways that are priceless. As you probably know, breastmilk has over 100 unique ingredients that cannot be duplicated in formula. And, being fed at the breast cannot be duplicated by anybody. The love, security and comfort that a baby feels at their mother's breast will make for a strong, secure and independent child and adult in the future. So, my advice is to breastfeed him as long as possible. You won't ever regret it and you'll be giving your son the greatest gift of all.
Now, I do have to tell you as background, that before I had kids, I had NOT planned on ever breastfeeding. Then, after being told by a good friend about the incredible & unique experience, and after I read more info on the unmatched nutrition and prevention of diseases for a lifetime...I decided that I HAD to breastfeed. I was determined to make it work, even though my mother and mother-in-law had not, nor most my friends. I had a tough time the first few months. However, just around the 4 month or so, is when it becomes like second nature for you and your child. And, in fact, the most wonderful comfort for you both really is experienced in the months just ahead. I set the goal of getting to 6-months and then when I got there I set the goal to 1 year. I ended up breastfeeding much longer. The World Health Organization recommends two years the American Pediatric Assoc. recommends a minimum of 1 year and in other countries they breastfeed even longer. There is even significant scientific data to show that as long as you breastfeed, there continues to be add-on benefits for you and your child long-term. If you feed even as long as 6 months, then you as the mother will reduce your future chances of breast cancer. Of course, the list of benefits goes on and on.
I'm sorry for being so long-winded and I don't mean to put any pressure on you. I don't know your circumstances but only wanted to share my passion for the unbelievable gift of the breastfeeding relationship between mom & child and the nutrition/prevention benefits. I was converted from a mindset of NEVER going to breastfeed to now being a major advocate. Breastfeeding is a sacrifice, but also an unbelievable privelege that God gives ONLY to Moms. Treasure every moment, because once its gone, you can't go back and give the priceless gift again.
In regard to the relationship with their Daddy, I totally understand. My daughter is a "Daddy's Girl" too. But, make your breastfeeding decision based on just the basics that it is the BEST thing you can do for your child. All of the nurturing you give to your child along with LOVE, quality time and attention will build your relationship with your kids long-term too.
Something that you may not be able to control right now, is to be a "stay-at-home" Mom. If you were able to, this decision would provide you with the quantity and quality of time to spend with your children and fostering an unmatched short-term and long-term relationship too. I was a corporate executive before becoming a Mommy at a late age (we had tried for years). Even though it was hard in many ways to walk away from the success I had had, what I knew how to do best and of course the financial contribution to the household, we made the sacrifice and have been doing so for 3 years. I will never regret the time I have to spend with my daughter, even though being an Executive was MUCH EASIER (I never thought I'd say that, prior to having my own children). And, now that my husband is out of work, it makes it even more difficult to not consider going back to work. However, I believe God's will for me it to be home with my children. Each person/couple/family has to decide what is best for them within God's will.
I pray for the very best for you in making these short-term and long-term decisions. You're doing a smart thing by soliciting counsel from others. Take care. Many Blessings - L.