We have almost no support, DH travels a lot for work and I do a bit again more recently.
DD went to crèche when she was 4 months old, full time, but near our offices so commuted with us daily. DH would drop in mornings, I would collect in evenings. I managed to mix-feed until she was 11 months old (expressed at lunch until 7 months, which was sent to crèche following day for 2 bottles of 4, and BF at home morning and evenings until 9 months, dropped morning feed first and finally the evening dream feed went at just about 11 months).
DD is a much loved DC, but is still an only DC, as that has suited us.
She's now 11. We've gone through early years, getting to primary school and afterschool club, summer camps, outside clubs, friends....managed them all, some better than others.
We have had VERY limited support from family. DPs and DPILs live 250 miles away, and have had very little practical involvement. Maybe 8 weekends where DD stayed with them so we could go away. A week in summer (that we can cover with camps if needed) to do things with them. DPILs came up twice when DH's travels clashed with mine to stay over (we had an aupair at the time but I never felt it was fair to ask them to do overnights alone - DH was away 2 weeks out of every 4 at the time). A DAunt living near us collects DD from afterschool hockey training once a week this year but we had juggled that ourselves before now.
We have made good friends with neighbours who have always said they're available to cover school/afterschool club emergencies or to call them if we need babysitting urgently. I found reliable teenagers for babysitting for social events a few years ago (and we had aupairs for 5 years so that was our babysitting before that). Parents in school have always tended to help each other out - in both emergencies and with longer term arrangement such as car pooling for the offsite hockey training.
Whenever DD was sick, we have just juggled who had more urgent meetings/priorities at work, changed things around and generally each done a close to full day (one would go in extra early and finish at lunch, the other drive to meet them with DD and swop to do the afternoon at work and a later finish than normal, and we'd both do more work at home once she was in bed - so if she was off for a week, we'd each get maybe 3.5/4 days real work done, catch up over the weekend, and just take whatever time off we absolutely needed). But we did have understanding bosses, who saw that we would get things done when needed and not just take time off on a whim, and work on catching up as well.
It was never part of our thought processes that we would have a lot of support, because we don't live close to them. My DPs lived 250 miles from their parents when we were young so had little or no practical support (and indeed were an ocean away for their first DCs first months) - they had 6! And my DF's parents also had far less practical support as they were 250 miles away from their parents, having 7 DCs, and in an era when that distance took all day to travel (few cars, not a great train service, so hours on a few buses to get all the way).
It didn't stop any of them having DCs. My DF and DGF were both senior people in their professions. My DM and DGM were both professionals before marriage, but admittedly were SAHM's after that (marriage bar for DGM, and DM was too remote in her new home to commute to work as the hospitals were in the city and she had no car initially and then too many DCs and few childcare options in those days).