I am not a medical professional at all, but my MFM (high risk doctor) had me start low dose aspirin as soon as I got a positive pregnancy test.
I am glad you are switching OB's, honestly, I would also try to get a consult with an MFM or perinatologist as well, they are usually the ones who recommend or don't recommend LDA.
Me (29) DH (30)
#1-Olivia Caetlyn-9-28-09-9-28-09, 23+2 wks, emergency classic c-section, class I HELLP, IUGR
#2- Lucas Oliver (rainbow baby)- April 2011, 36+2 wks, HELLP and pre-e free! (lovenox and LDA pregnancy)
#3-Matthew, late October 2012...mostly normal, 37 wks, (lovenox and LDA again)
My blog: http://www.butterflies-and-rainbows.blogspot.com/