Sounds like your LO has hit the 4 month sleep regression slightly earlier than most. My son hit it at around 13 weeks. Lowered me into false pretenses by sleeping 12 hours at night for 2 weeks before hand and then it all went t**s up! It does improve eventually but you may have to intervene and help your LO learn to sleep longer stretches - once LO reaches suitable age ofc.
I remember being in the same situation as you, and I was desperate for some insight into the future! I am going to give it to you (my son is now 3.5); As an earlier poster mentioned, its not linear, well not for a while. You are going to have months where you feel like youve really got this down pat and then months where you feel clueless again. However, you will find your groove. And the good moments will start to outshine the bad.
In terms of timelines:
6 months was a turning point for us. He was feeding well, sleeping well and was a bundle of personality, in his own beautiful bubbly baby way! Ah miss those days! (Never thought id say that, but hindsight is a wonderful thing)
10 months: The crawling some ppl hate this stage, but I personally loved it. Created a whole new landscape of things to do and enjoy with each other.
14 months: The really special, active connections happen - For example, my son held my hand for the first time to walk to nursery. May sound silly to others, but its a memory ill never forget. He actively seeked out my hand to hold. Bliss!
18 months: Hold on to your hats, your LO will enter toddler hood if not before and they are gonna give you a run for your money but in the best way! I loved toddlerhood. You get soooo much back from them and understanding their little minds and hearing them speak and communicate to you in full sentences is like no other feeling!
3 years: They are a fully fledged little, gorgeous person who will make your heart melt on a daily(minus the threenager moments) . I once read on here a poster say that 0 - 3 years is like a dark hole, but as soon as you start to edge closer and closer to 3, you start seeing the light. (Not sure if this resonates with you, but it did me as the baby months were not my favourite)
I know age 3 may seem like a long time away and it is but I promise you, there are sooo many enjoyable moments along the road. And you will make it. Perhaps with a slight side dish of PTSD but you will 😂as we all have.
It does get better and easier. But in the mean time, as every MN says, try to make some 'you' time and regularly.
Youve got this girl!