I am a single female, now 55 years old. First, remember that all life is meaningful. Secondly, the only way any of us make good use of our life is by doing everything for the love of God. It does not matter if we are married, a religious or solitary.
One thing to consider as part of your life, is whether or not the work you are doing is something you do enjoy while at the same time providing you an avenue to serve others in a Godly fashion. You can work in any occupation to do this. It is how you do your job that will matter, how you treat customers, co-workers, the general community.
If you are miserable at work or dread going to the current job, think of something else to do. But don’t put how much you make, or potential for promotion at the top of the reasons you select your form of employment. And believe me, you could land up on the poorer end of the economic sector, but you could be happier. (I found early on that being in management or supervisory roles just didn’t seem worth the time lost to family, and serving the Church, let alone the money. I opted to stay in the trenches if you will.)
If you don’t do a lot of volunteering look into that option. There is a lot of need out there for a lot of work, and people do appreciate and benefit from the effort. You can help out at animal shelters, visit nursing homes, visit the sick at home as a Pastoral Minister etc. There is always some way to lend a hand and add an aspect of service to others in your life.
Living modestly, being honest and kind, sticking to strong Christian morals, are all part of a “meaningful life.” The circumstances of our lives may be something we can do little about, we may have jobs we hate for a time, be ill, have to move, land up in huge dept, but how we handle these circumstances will determine how well our life matches that which Christ would want. This is how we find our “meaningfulness.”