Congratulations on your lilttle bundle and working towards a succesful breastfeeding relationship.

I agree with the girls, at this early age a routine is definately not required and it's normally within bubs best interest to have unlimited access.
DD2 is 11wks old and is only now setting her own routine, she will generally feed b/w 5 and 7am and the rest of the day is set in 3hr blocks from there, some days it's hot she wants it after 2hrs, others shes growing feeds 2hrly then might sleep for 4hrs.

I say just go with the flow as long as she is having good wet and dirty nappies, is sleeping well then your doing prefectly.

My DD also falls asleep, if you feel it's an issue it helps to undress them a little (weather and environment permittng), sometimes in warmer weather a cool cloth can keep them cool but also awake and possibly feeding longer.

GL with it all, you sound like your doing a wonderful job!