I can understand how you feel.
This is a big event for you - and you have occupied your thoughts with it for some time. Your mum may feel the same, but may be nervous about seeing you.
Some people, particularly older people, hide their insecurity in a show of hiffiness and indifference - which she may not really be feeling.
Try not to let it colour your anticipation, and be prepared for your mum to be a bit 'cold' at first - which again is her way of dealing with an unusual situation where she feels uncomfortable, and unsure of how to behave.
Be patient, be yourself, and I am sure it will all work out just fine.