OP l do think your worries are reasonable ...if you really want children l would not wait, some are lucky enough to conceive close to 40 but statistically many are not..
.take a look at the statistics, and have a really hard think about going it alone as opposed to hoping to meet the right person sooner rather than later.
I have many friends who waited for love and are childless in their early/mid 40s and it is heartbreaking to see.
INTHEKITCHENSINK has great ideas if going it alone is something you cannot face... but
I knew l really wanted children by 33, and was making plans to go it alone when l met my DH,
however, l was financially stable with a job that could be flexible and a home with a very low mortgage big enough for a family. I was prepared to move closer to support and change my lifestyle dramatically.
Because of my commitment to having Dcs, l spoke freely to Dh about my priorities pretty soon, as l was not prepared to settle down with someone who did not want children or assumed l had loads of time and left it too late..we started trying at 34.
as it turned out l had loads of conceiving issues and it took until l was 37 and 39 to have my Dcs....to this day l consider myself lucky beyond belief, as every year that went by my fertility was reducing...if l had known how fantastic Dcs were l would have tried earlier and had more!
If you really want this make it a priority, rearrange your life to make it happen, who knows you may meet the right person in time, but if not you will have your Dcs ..