That would probably be more ideal though tedious, will give you a better picture of your holdings and cost.
Currently I use the following which you can consider,
Stockmarketeye - Has a desktop program and a App as well, not as fancy an interface but it allows synchronization which I find very useful. Prices are taken via Yahoo. I can create multiple watchlist which is very handy for counters I am tracking.
Stocks Cafe - This calculates for dividends and comes up with your overall P&L, web based platform but I find the P&L displays very intuitive. Good if you are a dividend investor.
I could spend sometime and dig into my IBKR statements and update the actual buy transactions, maybe then the pl chart will make sense.