New infant seat or go straight to convertable?

TTC #2 due 3/29

I don't have my old infant seat base anymore, because I thought I would never get pregnant and figured someone should get use out of it before it expires! And I thought I would just go straight to a convertable seat anyway, my son is almost out of his and it starts at 5 lbs.

So the plan is to get him a 5 point harness high back booster and put the new baby in the convertable. I think baby wearing makes the most sense for our family right now, it will be easier to chase after an almost 4 year old with the baby in a sling or carrier, than lugging around the infant seat!

But part of me says just get the infant seat even though you will only use it a few months! Ugh I wish I hadn't gotten rid of the base. The base itself runs 65-85!