I know it can be frustrating, but don't be too hard on yourself or on your daughter. She is still young to be potty trainging so be glad that she has expressed some interest. I also have a two year old daughter (almost 25 months) and she started showing an interest in potty training at a very young age. Does your daughter stay dry at night and/or during nap time? I have been told that that is one way to determine if they are ready to train (but certainly not the only sign).
With our daughter, we started letting her sit on the potty at less than a year - not to try to train her, just so that she would not be scared of it sinced we did not have or plan on getting a small child potty. From 1 year she has be off an on using the potty. We have had many ups and downs in the process, but have just tried to be patient.
By this past Christmas, she was consistently staying dry at night and when napping. We talked about wearing "big girl underwear" and bought her some. At first we put it on over her diaper, then under her diaper (when we were going out or she was going to "school". At home we were doing just the underwear/panties. I would then watch her carefully for signs that she needed to go or suggest it to her. Then her teachers said it was fine to wear just her underwear and they would change her if she had an accident. She was doing really well.
Then in February things started changing, she started protesting going to the potty, saying she didn't need to go and crying at the suggestion (at home only) and I tried not to force her as I wanted it to be a positive experience. She also started pooping in her underwear which she had not done in the prior two months. We would go a few days with only 1 or no accidents to a couple of days with 5 or 6. It was very discouraging especially since she (nor I) wanted to get the diapers back out. I think some of it was she became a little more used to using the potty and then would be distracted playing and would tell me right after she went or right as she started.
At school it worked for them to let her pick out a sticker each time she went to the potty. At home, once I knew that she could do it because she had been, when she kind of went backwards, we started offering her a special treat - like 3 M&Ms or Skittles and going potty was the only time she got that treat. That worked for a little while, but my child doesn't appear to be real reward motivated at this point. We tried switching up the treats to keep some variety and make it more interesting for her.
If I know that it is about time that she should need to go, now I sometimes have a couple of her little plastic or stuffed animal that sit on the sink and cheer her on telling (in different voices)her things like "Way to go" or "good job" as she pees or poops and when she is done they may give her a kiss or she can give them a high five. I also have pretended to put her on the potty upside down or sideways like I don't know how to do it. She laughs and then I get her to tell me the right way to do it and she will sit. Once she is sitting she generally goes. The other thing that I have done is let her show her dolls/animals how to use the potty and even hold them over it so they can have thier turn. She then gets to wipe their little bottoms and it becomes kind of fun (but there was a short point that she only wanted her animals to go).
She still has some accidents especially when I am not there or she is very tired. But I think we are on the right path again. We have just gone 4 days/5 nights with no accidents including two days at school.
I hope some of the things that worked for us will be helpful for you. You may need to keep reminding her simply becuase she is busy doing other things and doesn't want to stop playing or gets distracted from the feeling of needing to go especially if it is not so new. I still ask/suggest that my daughter go every 2-4 hours (if I do it much more than that she gets discouraged becuase she seems to feel like we were just there) or before nap time, bed time, bath time or going out and after waking up. When we are out if she has not been in a while we have to go check out and see what kind of potty is where we are which makes it kind of a game (right now it is almost always at my suggestion).
My biggest suggestion is to be patient (and remember many people arenot lucky enought to even start this process for several months to a year later than you are) and try to keep it positive for you and her. Make it fun and really praise the good, even if she tells you but has an accident. Tell her that she had an accident, but that it was really good for her to let you know that she needed to go. You can always tell her that accidents happen, but lets try to tell mama little bit sooner so that her big girl underwear/panties and clothes don't get wet or messy the next time. If you decided to give a special treat, make sure you give it to her when she uses the potty and not just when she tells you she needs to go (unless you want feel that would help her communicate it better).