Tsp and Roth vs private brokerage

I currently have a managed ira that I max out and a tsp roth that I am putting 20% of base pay into (799.8). Additionally I put $430 a month into my private brokerage (historical return is 17.5%- almost all etf’s).

I currently have about 15k that I need to get into the market from my saving. My question is should I increase my tsp substantially for the next few months and use that 15k to subsidize my living expenses or should I put the 15k into my private brokerage account. The main reason I’m leaning towards brokerage is the availability to use it in the next few years.