If it helps, the summers are the hardest bits. All my 'mummy friends' who have pre-schoolers hate the summer because everything stops and becomes geared up to school aged DCs, it means you have a couple of months of nothing to do, while everyone is saying how lucky you are you can go on holiday outside the school holiday times - so you don't even use a couple of those wasted weeks away...
I've just had DC2, and it's sooo much easier this time round, because those casual friends to have a chat with at mum and baby groups I me the first time round, are now friends I've known for 3+ years, and we are getting to the support stage, eg. I've had their DCs over on moving days and when their childcare feel through on a day they had an important meeting at work, they've been the ones I cried on when i had a MC because unlike child-free older friends, I knew they'd "get it", they are the ones who've turned up after I had DC2 armed with hand-me-downs from their DDs (I had a DS first time round), cake and offers of taking DS for an hour or so to give me peace. When DD is old enough to be left, we'll restart our babysitting swaps in the evenings.
Dont get me wrong, many toddler group friends are still at the polite chat stage, nodding and saying hello when we pass in the street, but a small group have turned in to 'real' friends.
It's harder now for our generation I think, because it's less likely we'll live near family, if we do, then parents, sisters and cousins are more likely to be working, old friends are also unlikely to be housewives so again, not available in the day, and with people having DCs older for the last couple of generations, grandparents aren't people in their 40s who are full of energy to help out, but often close to being pensioners. With people having smaller families, the chances of a close friend or relation having a baby at a similar age to yours to share the stages with is unlikely.
However, set against that, my mum was shocked how many baby and mother groups there were for me to go to, very few churches ran them when she was a young mum (now I think every church in our town has one), there wasn't baby or toddler classes or activites, you just went to someone else's house - so if you didn't have a lot of family near by who were around in the day or old friends with DCs, you really were stuffed.
It's a month until all the groups restart in September, have an actitivty a day mapped out from the first week the school kids go back. You'll find you enjoy your time so much more if there's a structure to your day.