Hi everyone, thank you for the input.
I don't expect my parents to pay for anything, so when my mom offered the $2K I was shocked, but grateful. My parents own a beauty salon and right now business is slow (but it always is end of September early October) and they get freaked out about money. I think since we are both Hispanic our tempers flare much quicker and we both get excited. This is our downfall. Thankfully I have a great relationship with my mom and I can talk to her about things after we get mad.
I called my mom just now and talked to her. She was very upset and crying and I told her that I was sorry I hung up on her. I expressed how I was shocked at how she changed her mind so quickly. She told me that she can not afford $2k right now and was stressed out about it. But she will help in any way possible. I told her I would definitely pay the difference if there is any. She feels bad cause she wants to pay for everything and at the moment is unable to. I told her not to worry about it and we will work it out. Plus, I am not going to start looking for dresses until January. I feel so bad right now, I didn't want to make my mom cry.