I just wanted to jump in and comment about the issue with your mom.
I truly think you should tell her that she is making you feel pressured. Tell her that you have already planned on giving her some money but that you feel it is unfair for her to expect a certain amount. You need to "own your reality", say how you feel, because like a wise person once said to me, when you don't say how you feel to someone, the only person you are hurting is yourself.
I would let her know that you want to be excited about this, but feel it is difficult when everyone expects something from you. You need to have your moment. I really think if you are assertive with her, tell her how you feel, she might back off. Hope it works out. You deserve your moment of happiness!