Dunno if this will help, but ...
You sound like a bootstrapper - meaning, you don`t really have the capital to invest in staff and their required resources. So two things. The first is that you need to reinvest a part (significant) of your cashflow into adding capability and that looks like, in your case, staff. Tough to make money as a solo-op. You can make money if you have intellectual assets, or real asssets, but for a bootstrapper, the most common way is through adding people and getting a cut of the value that they provide to your client base.
Second, consider a partner. The increased flexibility and specialization can provide benefits to both partners, and make the operation more viable and sustainable, despite sharing the income. Be careful in your choice of partner though - have a business plan so you are both on the same page, and a decision framework is clearly in place. And yes, you will probably need a partnership agreement.
Third - if this does not work, consider a strategic alliance with another independent. This goes well beyond using freelancers, but stops short of co-mingling business interests.
Try to act sooner rather than later - guessing from the tone of your post, there is a possibility of burn-out on your horizon. Getting control of the situation now might restore your drive and enthusiasm, even if you have to sacrifice a bit in the shorter run.
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