Sleep isn't really linear. There will be changes through the next few years stemming from things like teething, developmental leaps, growth spurts, etc. That doesn't mean it isn't dreadfully hard to go from reliable sleep to interruptions through the night
That's around the age I start co-sleeping with my first. If that's something you want to explore, several of us here can guide you towards ways to make it safe and also not keep you feeling trapped at bedtime.
Best ways to get a kiddo to sleep better naturally are lots of time outside and/or in the water, ime.
You may want to put them on a little potty at the first wakeup. Sometimes that bit of a breeze on their bottom is enough to stimulate them to pee and that will allow them to get back to sleep more deeply.