I am five feet tall (on a tall day) and have never had a problem finding a suitor(s). I didn't have a problem at 115 pounds, 135 pounds, or 175 pounds. I probably had more of a problem with attracting too many men.
At 175 I did not feel my best. I have lost weight over the last year and am heading closer to 135. I can say that my attitude about myself was different at that time (upper weight level). There are women who have confidence issues at lower weight levels, higher weight levels, and there are women who never have those issues (that's the type of woman I wish I had been.
I think that there are some things that women can do to attract members of the opposite sex. I don't think that those things differ based on the size of the woman.
A nice outfit, a pleasant attitude, a smile, knowing how to flirt, and knowing how to give a man a compliment can go far. Men are like buses. They always come around. What one man doesn't like, one thousand more will. Dating is almost like a numbers game, you have to meet and dismiss the toads so you can find a prince. There are still some kings out there. Give a man a chance to tell you who he is by his actions (and not just his words). If he's not the right one, ditch him and keep it moving. If you are not attracting any men or the right men, ask your friends to critique you. Ask them why they think you are not attracting anyone and what they think you could do differently. Listen to the comments people are saying to you and make changes. I could write a book.