Should I try to get her back into her old routine?

My daughter who is nearly 5 months had been in a good routine during the day, she would feed every 3hrs then 2 hours after the start of each feed go down for a nap (she would only last 30-40 minutes but was very happy and wide awake after that).. for example:
3pm feed
(play)
5pm sleep (30-40 minutes)
6pm feed

The last couple of days she has been falling asleep after her feed in the morning (around 9am) which kind of put her out of whack for the rest of the day. Because by the time her next feed was coming near she was becoming tired and hungry then didnt feed particularly well. She sleeps in until 8:30am normally (even though up a couple of times through the night until then) so she shouldnt be so tired in the mornings.

Should i be keeping her awake after her feeds so she (hopefully) gets into her old routine which was working really well? Or should I just go with the flow and let her lead... i would normally do this with most things but I cant see it as being the best for her because she is getting unhappy as the next feed approaches and she has been up so long.
Would this change be due to growth spurts or something?

I have always preferred to let my DD Nina lead me. They change their routines so much, that I've found it easier to do it that way.
She could be changing due to a growth spurt, and you may find that after she's had the growth spurt she might go back to her old routine.
My suggestion would be to try a few different routines that will suit her at this time, as the current one isn't suiting her anymore.
Good luck

As Jodi said, I would follow her lead. Both my boys went down for their first sleep really soon after waking up in the morning, in fact DS2 still does if he gets the chance. But by changing that first sleep, it means that everything else might change too. You might need to do the next feed earlier too etc. In fact my boys often eat lunch at 11am, there is no need to stick to "traditional" meal times, just follow the tired and hungry cues and soon you will have a new routine which works. But of course, it will change again soon enough!! GL, it gets easier!!