EK is a "one third caster", that drags down your ESL (Effective Spellcaster Level).
This is explained here:
https://bg3.wiki/wiki/Spells#One-third_castersWhen multiple classes with the Spellcasting feature are chosen for a character, the creature's total ESL is instead the summed ESL of every individual spellcasting class they have taken a level in, each rounded down.
Hence (the way I understand things) a Paladin 2/Eldritch Knight 2 has an ESL of 2 - 1 from Paladin (0,5x2=1) and 1 from EK (0,33x2 = 0,66 rounded up to 1).
The EK will not generate anything extra until 6th class lvl, the Paladin - until 4th.
Only at character level 6 - Paladin 4/Eldritch Knight 2 - ESL would be 3.
If you wish to have many Spell Slots for Smites, then multiclassing into Bard is recommended, as these are Full Casters. And 2 sub-classes get a 2nd Attack at 6th lvl.
