OK...first thing, tell your Mom to back off. I had a similar situation w/my mother-in-law and the best advice I can give you is to ignore her and all of the other "experts" out there. Kids will potty train when they are ready...period. We were getting pressure when my nephew, who is 9 days younger than Emily, started going around age 2 (but it took him almost 9 months to get good at it). We also tried early (age 2), but met resistance from her (literally screaming) and decided to wait for a few months. When we tried again, it was the same thing, so we stopped.
We would continue to talk to Emily about it, though. EVERY time we changed her diaper, it was something to the effect of, "You know, big girls go pee-pee in the potty" or, "Emily, Mickey Mouse/Disney World likes big girls who pee-pee in the potty" (we are going in December and she is VERY aware of this fact) or "You are getting soooo big! Too big for diaper; those are for babies like Haley" (my other daughter who is one). This conversation was always followed up by the question, "Do you want to try to go in the potty now?" During one of these conversations, Emily said yes! We raced to the little potty and she went. It was AWESOME and she was trained in 3 weeks (except for poopies..see below!). My daughter is 3 and a half and she JUST now is potty training and doing great. (She still wears a pull-up at night and naps...for now).
Second...GET HER NAKED! If she has something she can pee in, she will. You WILL have accidents, but once she has the unpleasant feeling of pee running down her leg, she will get the idea. Keep asking her all the time if she has to go, that is key. If she is reminded, the messes are less likely to occur. We got the Fisher Price training potty and it was helpful; it plays songs and such and is a great tool. We put it out in our bathroom before we even thought of starting to potty train, just to get her used to it and she thought it was a blast to play with. She also would sit on it (fully clothed, of course!) when we would go and learned the steps.
Third...NO MORE DIAPERS!!! Go to the store and buy Pampers Easy-Ups or some variety of pull-ups that she can wear like big girl panties for naps and overnights and trips out of the house. If you want her out of baby-mode, don't enable her by giving her diapers. Our daughter threw fits and cried for 20 minutes to put a diaper on her, but we held form and just reassured her that the pull-up would do the trick. Eventually she gave up. Once she starts going somewhat regularly in the potty during the day, get her in big girl panties to play and such. No pull-ups during the waking hours!!!
Fouth..be patient and positive; this will try your patience like no other task you have encountered to this point. She will cry when she makes messes, she will throw tantrums when she has to go and is naked and will totally freak out if she has to poop, but you need to stay happy and positive the whole time. If you cave even once, you will start the process all over again.
Fifth...pooping in the potty took a few weeks after the whole pee-pee part got good. It is a scary thing for kids and needs to be addressed as such, but also with a LOT of [positive reinforcement. While we were waiting for this miracle to occur, we would give Emily a pull-up when she told us she had to go poopie. Then it came off and the big girl panties went back on. She was good with that. We finally convinced her to try the poopie/potty combo one night and when she did it she was so excited!!
Lastly…recognition and rewards. Emily loves M&Ms, so we stopped giving them to her except for when she went in the potty. It is a super cheap reward and she loved she could have sugar at all hours of the day! We would only give her about 5 or so and she looked forward to it. After awhile, though, she didn’t need it every time and then we stopped all together. We also had BIG rewards in place. The first time she went pee-pee in the potty, we took a trip to the toy store. When she went pee-pee in the BIG potty; ditto. She got to pick the toy (within reason) and then we did it again for the poopie in the potty. Now she will go in any potty, anywhere and we have moved the little one to storage to wait for round 2 with Haley next year.
Sorry this was so long, but I get really frustrated with those people out there that say kids should be potty trained or any other benchmark by a certain age. How many adults do you see wearing diapers to work or throwing back a baby bottle at the office? They will learn and accomplish great things on their own time, so relax, enjoy your daughter and good luck!