Tanya has always dreamed of having a child of her own. "I've wanted to be a mom since I was a child," she told "20/20's" Elizabeth Vargas, "I just loved children my whole life."Tanya's journey to motherhood began when she was just 19 and was forced to make the toughest decision of her life, one that still haunts her 21 years later. She became pregnant and gave her child up for adoption.It was not a decision that came easily, but at the time, it felt like the right thing to do. She wanted her daughter to have a family that would love and provide for her while Tanya could focus on school and a career. But after the adoption, she became sidetracked and says the decision "changed me forever.""I spent my twenties being a little bit lost… very sad that is a decision that I had to make," she said.In her 30's, Tanya's life began to take shape. Her career in finance took off and she was in a serious relationship that she hoped would turn into marriage and a family… until one day her boyfriend told her that he did not want to have children. That news came as a "huge shock" to Tanya and resulted in the end of their six-year relationship, leaving her single and childless at 39. That young girl who once gave up her child for adoption had become a woman who now found herself desperate for a second chance at motherhood."I have a hole in my heart," she said. "If I could have another biological child, that I could have the chance to be her mom, it would at least make me feel a little bit better."After a visit to the doctor, she was encouraged to waste no time getting pregnant."I didn't want to take the chance of never being a mom," she said. So she turned to sperm banks where she would go on to spend between $60,000 and $70,000 on vials of sperm, doctors' visits and inseminations. "I didn't have any infertility insurance at all, so I had to pay for everything out of pocket."Throughout the process, she became pregnant three times but each one resulted in a devastating miscarriage. At that point, she was out of work and had depleted her savings. Running out of options, she turned to the Internet, where she discovered a site called Free Sperm Donor Registry.There, she found hundreds of men looking to donate their sperm to women in need… and it was totally free. She created a profile for herself, and within no time, men were reaching out to her, interested in providing her with their sperm. One donor caught her interest."We spent weeks emailing and talking on the phone and really getting to know each other," she said.Eventually, they agreed to meet and Tanya found herself conducting the interview of a lifetime—over dinner and wine."We were both shaking as we were lifting our wine glasses," she remembered.They revealed a lot about themselves to each other and what started as an interview, ended as a date.Soon, their relationship evolved into more than what she initially intended."I hit the jackpot," Tanya said of her donor. "I never imagined that I would have gone on this website and found someone so wonderful."Though it was never her plan, Tanya and the donor started sleeping together. They exchanged STD results before consummating the relationship.Tanya confesses that she thought it was "crazy" at first but says, "People have one-night stands and they have babies all the time. I made an adult choice and he and I have come together for a common reason to do this."However, Tanya has made it clear to him that if she becomes pregnant, she is the only legal parent to the child."I wasn't on that website to find a boyfriend or husband or a father of my child," she firmly said. "I was on the website to find a wonderful person that was willing to provide me free sperm."With motherhood her number one priority, Tanya has also begun working with an adoption lawyer and has even set up a website -- www.babyfortanya.info -- where people who have information on adoptions can contact her. She hopes her biological daughter, who is now 21-years old, might track her down through the site.However it happens, Tanya is determined to have a baby. "I'm a fighter and I'm not ready to give up…. I just hope that the end result is me being a mom."