I really think LV should make a size 27 1/2. There is a huge size difference between a speedy 25 & a speedy 30.
I think you should get the 25 if you like it. Always get what YOU like, otherwise there'll be regrets.
I think the 30 is perfect on you. I carry DE speedy 30 and I'm 5'4 and in shape - and I've literally used it for a year and a half straight. it's big enough to carry everything, big enough on your frame, yet small enough to take out to dinner or to get cocktails w the girls. I think you made the right choice!!
Personally I like the 25.....I went and tried on the 30 and felt like it was to big. I am also 5'3. Yes I am like the only one that likes the 25. LOL But unless I start carrying everything I own with me, I will stick with my 25