I'm a fed employee as well. Would recommend looking at taking a retirement seminar as there are a lot of fed complicated/specific program info that you need to know...TSP is one aspect of this...you may also want to know repercussions of retiring early on your pension and other fed benefits, such as health insurance. For instance there is a rule that you need to have an annuity to pay the insurance premiums and need to have health insurance the last X years before you retire to keep it into retirement.
When looking for a good seminar, keep in mind that many give a free or low cost half-day seminar as a teaser to get you to buy their retirement planning services. Find a good one that lasts a couple of days that gives you all the info and get it paid for by the agency you work for. You can even organize a seminar for your coworkers and help them out if there is enough interest in your office. You may want to find a good financial planner with expertise in federal benefits as well, before you take the step to retire so you are certain your assumptions are correct. It is very unusual for fed employees to retire with less than 30 years (seems like many here are in the 30-40 range) and the seminars are often suited towards people who are going to retire in a couple years (and are still clueless as to what their benefits will be after working 25-35 years!). Anyway, a seminar is a good place to start.
TSP is a great place to put your money, it has very low fees on the funds and no cost to trade or reballance your account. Not a bad idea to have a separate Vangaurd account though--especially as a fund to live off while money is locked up in the TSP before your 59.5 (I believe there are some ways around this that I need to read up on). When you retire, you can decide to remove all your funds from TSP into another retirement account, get an annuity, or keep it there until you are 59.5 (i think) when you have to start receiving fixed payments.
As others have said, you are putting all your money into stocks (C, S, I, VFAIX). Would read up on asset allocation and consider adding some bonds (F, or other Vanguard Funds) to your portfolios.
You are doing great...wish I was in such a good situation at such a young age.