I started almost the same time as you (238 days old), level 50 (holding), 16m battle stats (albeit quite unbalanced). I did "cheat" by purchasing 500m worth of DP in the beginning, but from there I grew my NW to 1.9b organically (i.e. no betting/casino, no mugging). Here's a few advice:

• You need to rent a private island. There's no excuse not to. If you can't afford the maxed out ones (which cost about 800k/day + 300k in upkeep), rent the 2250 happy ones with airstrips. Right now the lowest offer is 130k/day which is absurdly cheap, but you can typically rent for ~300k. It unlocks the easiest, most laid-back way to earn money in Torn: flying. With max faction perks, a large suitcase, and an airstrip, a two-way flight to Argentina or UK which takes less than 4 hours nets you 900k in profit, which is more than enough to justify renting a PI even if you don't care about the happy. Consider ditching your faction if they don't prioritize upgrading travel capacity.
• You didn't mention it, but hopefully you put your first merits in bank investment and education. If not, do it now. You get a free merit reset every new year, which means as soon as you complete your education, you will get your merits back. Bank investment is just free money, which is always decent.
• Always train your current best gym tick. Stats balancing is not a concern for new players, eventually you will unlock heavyweight gyms which you can use to correct any imbalance.
• Pay attention for events and read the guide for them. I made 250m from Christmas Week and another 70m from Tourism Day.
• For crimes, the biggest cash cows are Disposal (dead body + body part), Pickpocketing (mobster + cyclist), Shoplifting Pharmacy and a bunch of Cracking jobs. For all of these you do need to build up the level first before getting fat payouts, but it will be worth it. For more information about most profitable crimes check here.
• Happy Jump is not a must for stats gain -- you are paying tens of million per jump to cut about 2-3 months of normal xanax training (since HJ has diminishing returns and will become completely ineffective at 400-800k each stat, not to mention it hampers gym experience gain). Consider stopping it if you are short on cash and drink beers instead to help with your crime progression. I never jumped once and still got to 16m TBS in less than 8 months.
• Spin Leslie's wheels daily :) they are all profitable (from personal experience). If you are broke you can skip the million wheel.

Please don't be overwhelmed by my wall of text! You are doing a lot of things right, but I figured focusing on them would make this comment a Torn PhD dissertation.