TOTALLY!!!
I never got my period back until month 14-15 so 9.5 sounds early, ha ha.
Good for you for nursing twins, btw, keep it up as long as possible as the longer you nurse the more brain-boosting they get and the more protection from cancer, asthma, allergies, obesity, the list goes on and on THEY get AND the longer you nurse the more protection from breast cancer you get. Even if it's only once a day, hold onto it as long as possible (and def hold on until cold/flu/gi bug season is over!!!), the health effects are so great and milk from a cow doesn't give them any protection (or you) so great to keep going.
I hope this helps! Actually there is a term 'natural child spacing' that discusses how around the world moms who nurse their children like other mammals (for as long as they need it, not just on moms time-table) will naturally have babies 2 or more years apart, naturally.
From www.kellymom.com (awesome site!)
"How can I maximize my natural period of infertility?
Timing for the return to fertility varies greatly from woman to woman and depends upon baby's nursing pattern and how sensitive mom's body is to the hormones involved in lactation.
Breastfeeding frequency and total amount of time spent breastfeeding per 24 hours are the strongest factors leading to the return of fertility: a mother is more likely to see the return of fertility if baby's nursing frequency and/or duration is reduced, particularly if the change is abrupt.
In some populations, research has shown that night nursing slows the return to fertility.
One study showed that mothers who were separated from their infants (but expressed milk to provide 100% breastmilk for baby) had a higher pregnancy risk (5.2%) during the first 6 months (Valdes 2000).
The introduction of solid food can also be a factor in the return of fertility. Once baby starts solids (if mom's cycles have not returned), the natural period of infertility may be prolonged by breastfeeding before offering solids, starting solids gradually, and not restricting nursing.
You can achieve higher effectiveness by practicing ecological breastfeeding:
keeping baby close
breastfeeding on cue (day and night)
using breastfeeding to comfort your baby
breastfeeding in a lying-down position for naps and at night
using no bottles or pacifiers
If you practice ecological breastfeeding:
Chance of pregnancy is practically zero during the first three months, less than 2% between 3 and 6 months, and about 6% after 6 months (assuming mom's menstrual periods have not yet returned).
The average time for the return of menstrual periods is 14.6 months.
Moms whose cycles return early tend to be infertile for the first few cycles. Moms whose cycles return later are more likely to ovulate before their first period.
Source: Natural Child Spacing and Breastfeeding by Jen O'Quinn "