Dear Eating and Watching,
You love your life, you love your living situation, but you wish you had more money? If I had to compare that set of circumstances with the people who hate their living situations and still wish they had more money or the people who have adequate funds but are totally miserable, I'd say you're doing all right! You say you, "know it's the best decision for you," but I'm not sure how or why you know that based on the other information you've provided.
It sounds to me like you're doing great and maybe there are some outside pressures telling you that you need to be saving more money (and really, who doesn't feel those pressures?!). Instead of talking yourself into giving up the independence that you really enjoy, consider what other cost-saving measures you can put into place in other areas of your life. Since you have your own place, maybe you can entertain your friends at home more rather than spending money going out. Look into cheaper cable or phone plans. Make yourself a budget and see your greatest areas of spending other than rent, then see if you can squeeze an extra couple hundred dollars from somewhere to put away toward savings, thus freeing yourself up to use the rest of your money as you see fit in the short term.
Another option is to find a cheaper place to live by yourself. If you're in a one-bedroom in a doorman building now, see how much you would save by moving into a studio in a brownstone. Consider what neighborhoods would still be acceptable to you but might be less expensive than where you are now. Also find out if you can save some rent in your current place by signing a long-term lease; some landlords are willing to forgo yearly increases in favor of having a stable tenant.
After you've thought through the options for saving some money while continuing to live alone, come back to the idea of having roommates. Make an alternate budget that shows shared living expenses. See how much you'd really be saving, and be realistic about what you'd actually put into savings or retirement or paying off loans. When you see all the numbers and options in front of you, you may decide that you can change your priorities for a little while and share your space to get the financial benefits. You also might realize that the savings aren't that great compared to what you'd be giving up, and you'll have a new and even greater appreciation for coming home at the end of a long day and putting your feet up without anyone looking over your shoulder.