Started a new campaign. Looking for help making my character more tanky (Conquest Paladin + Undead Warlock)

Hello! We have started a new campaign and decided to go in completely blind character wise. And you guessed it, we are frail. We have 1: a wizard, 2: a rogue, 3: what I think is also some form of rogue, and 4: me, a paladin (conquest subclass later on).

Luckily I had the foresight to make a character that's a bit of a jack of all trades. I started Paladin for the chain mail and I also have a greatsword. My original plan was to go warlock for both the range damage and the hexblade invocations but also for the theme, as my character is a dhampir and the undead warlock route would be really cool. These two classes give me a lot of room to play with and so I'd like to lean more tanky for my party.

Backstory and idea in short: She is a dhampir who grew up with her human mother because her father was so ashamed of having a child with a human he abandoned them early. Her mother taught her order, discipline and justice whereas her father believed fear was the purest form of power. She then becomes a paladin to destroy (moral) weakness like her father and his clan. Later she finds a powerful vampire lord who helps her control and understand her vampiric nature and grants her powers (which is where the warlock part comes in).

My stats are 14 str, 8 dex, 17 con, 10 int, 10 wis, 15 cha. In terms of being a tank I also have 16 AC and the tough feat (2hp extra every level!).

The orignal plan was to get first level paladin and then go hard into warlock but now I'm thinking maybe go for more paladin levels first. For example I can get a defense fighting style at level 2 which gives me 17 AC. I could also get a shield but the idea of an undead paladin woman with a huge sword is simply a bit too cool. I could also get an extra point in strength at level 4 so I can wear better armor but I'd be spread really thin between high str, con, and cha.

Any ideas on leveling order and ways to become the parties true tank without sacrificing any flavour would be highly appreciated! <3