General rule of thumb - for combating the 45min naps: under 4mos, decrease A time and over 4mos increase A time.
So Marrisa Mom, less A time and CW more A time.
CW-When i was really in thick of it, i worked at it non-stop for a week or 2 and if she woke early i did shh/pat or pu/pd (mainly shh/pat) for the remainder of the nap time. If successful, shout for joy (quietly). If not, then get her up and restarted my 4hr EASY w/ 2.25 of A time.